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		<title>Torque Acting on Bar Magnet in Uniform Magnetic Field</title>
		<link>https://thefactfactor.com/facts/pure_science/physics/torque-acting-on-bar-magnet-in-uniform-magnetic-field/4792/</link>
					<comments>https://thefactfactor.com/facts/pure_science/physics/torque-acting-on-bar-magnet-in-uniform-magnetic-field/4792/#respond</comments>
		
		<dc:creator><![CDATA[Hemant More]]></dc:creator>
		<pubDate>Mon, 11 Nov 2019 11:28:29 +0000</pubDate>
				<category><![CDATA[Physics]]></category>
		<category><![CDATA[Bar magnet]]></category>
		<category><![CDATA[Electric circuit]]></category>
		<category><![CDATA[Fictitious poles]]></category>
		<category><![CDATA[Geometric length]]></category>
		<category><![CDATA[Inverse square law]]></category>
		<category><![CDATA[Like poles]]></category>
		<category><![CDATA[Magnetic circuit]]></category>
		<category><![CDATA[Magnetic dipole]]></category>
		<category><![CDATA[Magnetic dipole moment]]></category>
		<category><![CDATA[Magnetic field]]></category>
		<category><![CDATA[Magnetic induction]]></category>
		<category><![CDATA[Magnetic intensity]]></category>
		<category><![CDATA[Magnetic length]]></category>
		<category><![CDATA[Magnetic poles]]></category>
		<category><![CDATA[Nort pole]]></category>
		<category><![CDATA[south pole]]></category>
		<category><![CDATA[Tangent Law]]></category>
		<category><![CDATA[torque acting]]></category>
		<category><![CDATA[Unlike poles]]></category>
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					<description><![CDATA[<p>Science &#62; Physics &#62; Magnetism &#62; Torque Acting on Bar Magnet in Uniform Magnetic Field In this article, we shall study the force acting on poles and torque action on bar magnet suspended in a uniform magnetic field. Force Between Two Magnetic Poles (Inverse Square law): If two poles of strengths m1 and m2 separated [&#8230;]</p>
<p>The post <a href="https://thefactfactor.com/facts/pure_science/physics/torque-acting-on-bar-magnet-in-uniform-magnetic-field/4792/">Torque Acting on Bar Magnet in Uniform Magnetic Field</a> appeared first on <a href="https://thefactfactor.com">The Fact Factor</a>.</p>
]]></description>
										<content:encoded><![CDATA[
<h4 class="wp-block-heading"><strong>Science &gt; </strong><a rel="noreferrer noopener" href="https://thefactfactor.com/physics/" target="_blank"><strong>Physics</strong></a><strong> &gt; </strong><a rel="noreferrer noopener" href="https://thefactfactor.com/physics/magnetism/" target="_blank"><strong>Magnetism</strong></a><strong> &gt; Torque Acting on Bar Magnet in Uniform Magnetic Field</strong></h4>



<p>In this article, we shall study the force acting on poles and torque action on bar magnet suspended in a uniform magnetic field.</p>



<p class="has-text-color has-background has-medium-font-size has-luminous-vivid-orange-color has-very-light-gray-background-color"><strong>Force Between Two Magnetic Poles (Inverse Square law):</strong></p>



<p>If two poles of strengths  m<sub>1</sub>  and  m<sub>2</sub>  separated by a distance &#8216;r&#8217; from each other in a vacuum, then the force between the two magnetic poles is given by</p>



<div class="wp-block-image"><figure class="aligncenter is-resized"><img decoding="async" src="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-53.png" alt="" class="wp-image-4805" width="112" height="44"/></figure></div>



<p class="has-text-color has-background has-medium-font-size has-luminous-vivid-orange-color has-very-light-gray-background-color"><strong>Problems
on Inverse Square Law</strong></p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example
&#8211; 01:</strong></p>



<p><strong>The force between two magnetic poles in the air is 9.604 mN. If one pole is ten times stronger than other, calculate the pole strength of each magnet. The distance between the poles of two magnets is 0.1 m.</strong></p>



<p><strong>Given:</strong> Force = F = 9.604 mN = 9.604 x 10<sup>-3</sup> N, distance
between poles = r = 0.1 m, Relation between pole strength m<sub>2</sub> = 10 m<sub>1</sub>,&nbsp;μ<sub>o</sub>/4π
= 10<sup>-7</sup> Wb/Am.</p>



<p><strong>To
Find:</strong> pole strengths = ?</p>



<p><strong>Solution:</strong></p>



<div class="wp-block-image"><figure class="aligncenter"><img decoding="async" width="214" height="223" src="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-51.png" alt="" class="wp-image-4803"/></figure></div>



<p style="text-align:center">m<sub>2</sub>
= 10 m<sub>1</sub> = 10 x 9.8 = 98 Am</p>



<p style="text-align:center"><strong>Ans:</strong> The pole strengths of magnets are 9.8 Am and 98 Am.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example
&#8211; 02:</strong></p>



<p><strong>What is the force of repulsion between two magnetic poles of strengths 1.6 Am and 7.2 Am separated by a distance 0.06 m in a vacuum?</strong></p>



<p><strong>Given:</strong> pole strengths m<sub>1</sub> = 1.6 Am and m<sub>2</sub> =
7.2 Am, distance between poles = r = 0.06 m,&nbsp;μ<sub>o</sub>/4π = 10<sup>-7</sup>
Wb/Am.</p>



<p><strong>To
Find:</strong> The force between poles = F = ?</p>



<p><strong>Solution:</strong></p>



<div class="wp-block-image"><figure class="aligncenter is-resized"><img decoding="async" src="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-52.png" alt="" class="wp-image-4804" width="139" height="145"/></figure></div>



<p style="text-align:center"><strong>Ans:</strong> Force Between Poles is 3.2 x 10<sup>-4</sup> N



</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Force Experienced by a Pole of Magnet in Uniform Magnetic Field:</strong></p>



<p>If we try to break the bar magnet at the centre and separate the poles, new poles are formed at the broken ends. It means it is not possible for us to separate the poles and study them individually hence the magnetic circuit is studied in analogy with the electrical circuit. Analogous to the quantity of electrical field intensity we have similar quantity magnetic field intensity. It is also referred as magnetic induction. The electrical field intensity at a point is defined as the force experienced by a unit charge kept at that point.</p>



<div class="wp-block-image"><figure class="aligncenter is-resized"><img loading="lazy" decoding="async" src="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-45.png" alt="" class="wp-image-4794" width="49" height="43"/></figure></div>



<p>By analogy,
we can define magnetic induction at a point as the force experienced by a pole
of unit strength kept at that point. Let the strength of the magnetic field be
B.</p>



<div class="wp-block-image"><figure class="aligncenter is-resized"><img loading="lazy" decoding="async" src="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-46.png" alt="" class="wp-image-4795" width="85" height="71"/></figure></div>



<p>Thus the
N-pole is acted upon by a force of magnitude mB and the south pole is acted
upon by a force of magnitude mB, in the opposite direction to that on the north
pole.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Torque Acting on Bar Magnet in a Uniform Magnetic Field:</strong></p>



<p>Let us consider a bar magnet of pole strength, ‘m’ and magnetic length ‘2l’ suspended in a magnetic field of induction B such that it is free to rotate about a transverse axis passing through its centre. Let θ be the angle between the axis of the bar magnet and the direction of the magnetic field.</p>



<p>The magnetic dipole moment of a bar magnet is given by</p>



<p style="text-align:center">M
= m . 2l …………… (1)</p>



<p>Now,
each pole of the bar magnet is acted upon by a force whose magnitude is given
by</p>



<p style="text-align:center">F = mB  …………… (2) </p>



<div class="wp-block-image"><figure class="aligncenter"><img loading="lazy" decoding="async" width="289" height="300" src="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-47.png" alt="Torque Acting on Bar Magnet " class="wp-image-4796"/></figure></div>



<p>The force acting on the north pole is equal to the force acting on the south pole but they act in the opposite direction. Similarly, the lines of action of these two forces are different, Hence they form what is called a couple.</p>



<p>The magnitude of the couple or moment of force is given by</p>



<p style="text-align:center">Torque ( τ ) = Force (F) . Perpendicular distance between the forces</p>



<p style="text-align:center">∴
τ &nbsp;=&nbsp;&nbsp;&nbsp; F&nbsp; . SP</p>



<p style="text-align:center">∴
τ &nbsp;=&nbsp;&nbsp;&nbsp; F&nbsp; . 2<em>l</em> sin θ &nbsp; &nbsp; &nbsp;
&nbsp; &nbsp;……………….&nbsp;&nbsp; (3)</p>



<p style="text-align:center">From
equations (2) and (3)</p>



<p style="text-align:center">τ
=&nbsp;&nbsp;&nbsp; m B . 2<em>l</em> sin θ</p>



<p style="text-align:center">∴
τ &nbsp;=&nbsp;&nbsp;&nbsp; (m . 2<em>l</em> ) . B&nbsp; sin θ &nbsp; ………………..(4)</p>



<p style="text-align:center">From
equations (1) and (4)</p>



<p style="text-align:center">τ
=&nbsp; &nbsp; M B sin θ</p>



<div class="wp-block-image"><figure class="aligncenter"><img loading="lazy" decoding="async" width="129" height="23" src="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-48.png" alt="" class="wp-image-4797"/></figure></div>



<p>This is an expression for the torque acting on a magnet kept in the magnetic field. The direction of the torque is perpendicular to the plane passing through .i.e. perpendicular to the plane of the paper.</p>



<p class="has-text-color has-background has-medium-font-size has-luminous-vivid-orange-color has-very-light-gray-background-color"><strong>Tangent
Law:</strong></p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Statement:</strong></p>



<p>If a bar magnet is free to rotate about an axis at right angles to two mutually perpendicular uniform magnetic fields of inductions&nbsp;B<sub>1</sub> and B<sub>2</sub>, then it comes to rest in a direction making an angle q with the direction of , such that </p>



<p style="text-align:center">B<sub>2</sub> = B<sub>1</sub> . tan θ </p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Proof:</strong></p>



<p>It is found that when a bar magnet is suspended in two cross magnetic fields, it comes to rest with its axis along the direction of the&nbsp;resultant of the two magnetic fields. Consider a bar magnet suspended in two cross magnetic fields  B<sub>1</sub>  and  B<sub>2</sub> .</p>



<div class="wp-block-image"><figure class="aligncenter"><img loading="lazy" decoding="async" width="300" height="168" src="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-50.png" alt="Torque Acting on Bar Magnet " class="wp-image-4800"/></figure></div>



<p>Under the action of these two magnetic fields the needle rotates through angle θ and come to rest along the resultant of these two magnetic fields.</p>



<p>In the equilibrium condition, the needle is acted upon by two torques. one due to the magnetic field of induction given by m B<sub>2</sub> .2<em>l</em>. cosθ and&nbsp;second due to the horizontal component of the earth given by m B<sub>1</sub> .2l. sin θ. Under the action of these two torques, the needle remains in equilibrium. Hence the two couples should be equal.</p>



<p style="text-align:center">∴&nbsp; m B<sub>2</sub>  . 2l . cos θ &nbsp;= m  B<sub>1</sub>  &nbsp;. 2l. sin θ</p>



<p style="text-align:center">∴&nbsp; &nbsp; B<sub>2</sub>  . cos θ &nbsp; =   B<sub>1</sub>  &nbsp;. sin θ</p>



<p style="text-align:center"> B<sub>2</sub>  =   B<sub>1</sub>  . (sin θ / cos θ)</p>



<p style="text-align:center"> B<sub>2</sub>  =   B<sub>1</sub>  . tan θ</p>



<p style="text-align:center">This relation is called as the tangent law.</p>



<p class="has-text-color has-background has-medium-font-size has-luminous-vivid-orange-color has-very-light-gray-background-color"><strong>Numerical Problems on Torque Acting on Magnet:</strong></p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example &#8211; 03:</strong></p>



<p><strong>A torque of moment 25 x 10</strong><sup><strong>-2</strong></sup><strong> Nm acts on a magnet suspended in a uniform magnetic field of induction 0.5 Wb/m</strong><sup><strong>2</strong></sup><strong> when making an angle of 30° with the field. Find the magnetic dipole moment of the magnet.</strong></p>



<p><strong>Given:</strong> Torque = τ = 25 x 10<sup>-2&nbsp;</sup>Nm, Magnetic
induction = B = 0.5 Wb/m<sup>2</sup>, angle with field = θ = 30°.</p>



<p><strong>To
find:</strong> Magnetic moment = M = ?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">τ
= MB sin&nbsp;θ</p>



<p style="text-align:center">∴
M =&nbsp;τ/&nbsp;Bsin&nbsp;θ</p>



<p style="text-align:center">∴
M = 25 x 10<sup>-2</sup>/&nbsp;(0.5 x sin 30°)&nbsp;= 25 x 10<sup>-2</sup>/&nbsp;(0.5
x 0.5)</p>



<p style="text-align:center">∴
M = 25 x 10<sup>-2</sup>/&nbsp;(0.25)&nbsp;= 1 Am<sup>2</sup></p>



<p style="text-align:center"><strong>Ans:</strong> The magnetic dipole moment of the magnet is 1 Am<sup>2</sup></p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example &#8211; 04:</strong></p>



<p><strong>A magnet of magnetic dipole moment 2 Am</strong><sup><strong>2</strong></sup><strong> is deflected through 30° from the direction of a magnetic field of induction 2 Wb/m</strong><sup><strong>2</strong></sup><strong>. Find the magnitude of the torque or couple.</strong></p>



<p><strong>Given:</strong> Magnetic moment = M = 2 Am<sup>2</sup>,&nbsp;Magnetic
induction = B = 2 Wb/m<sup>2</sup>, angle with field = θ = 30°.</p>



<p><strong>To
find:</strong>&nbsp;Torque = τ =?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">τ = MB sin&nbsp;θ</p>



<p style="text-align:center">∴
τ = 2 x 2 x sin&nbsp;30° = 2 x 2 x 0.5 = 2 Nm</p>



<p style="text-align:center"><strong>Ans:</strong> The torque acting on the magnet is 2 Nm</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example &#8211; 05:</strong></p>



<p><strong>A bar magnet of dipole moment 7.5 Am</strong><sup><strong>2</strong></sup><strong> experiences a torque of 1.5 x 10</strong><sup><strong>-4</strong></sup><strong> Nm, when placed inclined at 30° in a uniform magnetic field. Find the magnetic induction of the field.</strong></p>



<p><strong>Given:</strong> Magnetic moment = M = 7.5 Am<sup>2</sup>,&nbsp;, angle with
field = θ = 30°, Torque =&nbsp;τ =&nbsp;1.5 x 10<sup>-4</sup> Nm</p>



<p><strong>To
find:</strong> Magnetic induction = B =?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">τ
= MB sin&nbsp;θ</p>



<p style="text-align:center">∴
B =&nbsp;τ/&nbsp;Msin&nbsp;θ</p>



<p style="text-align:center">∴
B = 1.5 x 10<sup>-4</sup>/&nbsp;(7.5 x sin 30°)&nbsp;= 1.5 x 10<sup>-4</sup>/&nbsp;(7.5
x 0.5)</p>



<p style="text-align:center">∴
B = 4 x 10<sup>-5</sup>&nbsp;Wb/m<sup>2</sup></p>



<p style="text-align:center"><strong>Ans:</strong> The magnetic induction is&nbsp; is 4 x 10<sup>-5</sup>&nbsp;Wb/m<sup>2&nbsp;</sup>&nbsp;or&nbsp;4
x 10<sup>-5</sup>&nbsp;T</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example &#8211; 06:</strong></p>



<p><strong>A magnet of dipole moment 0.05 Am</strong><sup><strong>2</strong></sup><strong> is suspended so to move freely in a horizontal plane. Find the couple required to hold it at right angles to the Earth&#8217;s horizontal magnetic induction of 0.32 x 10</strong><sup><strong>-4</strong></sup><strong> Wb/m</strong><sup><strong>2</strong></sup><strong>.</strong></p>



<p><strong>Given:</strong> Magnetic moment = M = 0.05 Am<sup>2</sup>,&nbsp;Magnetic
induction = B =&nbsp;0.32 x 10<sup>-4&nbsp;</sup>Wb/m<sup>2</sup>, angle with
field = θ = 90°.</p>



<p><strong>To
find:</strong>&nbsp;Torque = τ =?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">τ
= MB sin&nbsp;θ</p>



<p style="text-align:center">∴ τ = 0.05 x 0.32 x 10<sup>-4&nbsp;</sup>x sin&nbsp;90° </p>



<p style="text-align:center"> ∴ τ  = 0.05 x 0.32 x 10<sup>-4&nbsp;</sup>x 1 = 1.6 x 10<sup>-6</sup> Nm</p>



<p style="text-align:center"><strong>Ans:</strong> The torque acting on magnet is 1.6 x 10<sup>-6</sup> Nm</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example &#8211; 07:</strong></p>



<p style="text-align:left"><strong>Calculate the dipole moment of magnet which when placed at right angles to the earth&#8217;s horizontal magnetic induction 2 x 10</strong><sup><strong>-5</strong></sup><strong> Wb/m</strong><sup><strong>2</strong></sup><strong> experiences a couple of 2 x 10</strong><sup><strong>-5</strong></sup><strong> Nm.</strong></p>



<p><strong>Given:</strong> Torque = τ = 2 x 10<sup>-5&nbsp;</sup>Nm, Magnetic
induction = B =&nbsp;2 x 10<sup>-5&nbsp;</sup> Wb/m<sup>2</sup>, angle with
field = θ = 90°.</p>



<p><strong>To
find:</strong> Magnetic moment = M = ?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">τ
= MB sin&nbsp;θ</p>



<p style="text-align:center">∴
M =&nbsp;τ/&nbsp;Bsin&nbsp;θ</p>



<p style="text-align:center">∴
M = 2 x 10<sup>-5</sup>/&nbsp;(2 x 10<sup>-5</sup> x sin 90°)&nbsp;= 2 x 10<sup>-5</sup>/&nbsp;(2
x 10<sup>-5</sup> x 1)</p>



<p style="text-align:center">∴
M = 1&nbsp;Am<sup>2</sup></p>



<p style="text-align:center"><strong>Ans:</strong> The magnetic moment of the magnet is 1 Am<sup>2</sup></p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example &#8211; 08:</strong></p>



<p><strong>A magnet of moment 0.6 Am</strong><sup><strong>2</strong></sup><strong> makes an angle of 30° with the magnetic meridian. Calculate the torque that tends to bring&nbsp; the magnet back to the meridian given that the earth&#8217;s horizontal field is 3.2 x 10</strong><sup><strong>-5</strong></sup><strong> Wb/m</strong><sup><strong>2</strong></sup><strong>.</strong></p>



<p><strong>Given:</strong> Magnetic moment = M = 0.6 Am<sup>2</sup>,&nbsp;Magnetic
induction = B = 3.2 x 10<sup>-5&nbsp;</sup>Wb/m<sup>2</sup>, angle with field =
θ = 90°.</p>



<p><strong>To
find:</strong>&nbsp;Torque = τ =?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">τ
= MB sin&nbsp;θ</p>



<p style="text-align:center">∴ τ = 0.6 x 3.2 x 10<sup>-5&nbsp;</sup>x sin&nbsp;30° </p>



<p style="text-align:center"> ∴ τ  = 0.6 x 3.2 x 10<sup>-5&nbsp;</sup>x 0.5 = 9.6 x 10<sup>-6</sup> Nm</p>



<p style="text-align:center"><strong>Ans:</strong> The torque required is 9.6 x 10<sup>-6</sup> Nm</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example &#8211; 09:</strong></p>



<p style="text-align:left"><strong>A torque of 5 x 10</strong><sup><strong>-3&nbsp;</strong></sup><strong> Nm is required to hold a freely suspended horizontal bar magnet with the axis at an angle of 60° to uniform horizontal field of induction 3 x 10</strong><sup><strong>-3</strong></sup><strong> Wb/m</strong><sup><strong>2</strong></sup><strong>. Find the magnetic moment of the magnet.</strong></p>



<p><strong>Given:</strong> Torque = τ = 5 x 10<sup>-3&nbsp;</sup>Nm, Magnetic
induction = B =&nbsp;3 x 10<sup>-3&nbsp;</sup> Wb/m<sup>2</sup>, angle with
field = θ = 60°.</p>



<p><strong>To
find:</strong> Magnetic moment = M = ?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">τ
= MB sin&nbsp;θ</p>



<p style="text-align:center">∴
M =&nbsp;τ/&nbsp;Bsin&nbsp;θ</p>



<p style="text-align:center">∴ M = 5 x 10<sup>-3</sup>/&nbsp;(3 x 10<sup>-3</sup> x sin 60°)&nbsp;</p>



<p style="text-align:center"> ∴ M  = 5 x 10<sup>-3</sup>/&nbsp;(3 x 10<sup>-3</sup> x 0.8660)</p>



<p style="text-align:center">∴
M = 1.925 Am<sup>2</sup></p>



<p style="text-align:center"><strong>Ans:</strong> The magnetic moment of the magnet is 1.925 Am<sup>2</sup></p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example &#8211; 10:</strong></p>



<p><strong>A short bar magnet placed with its axis at 30° to a uniform magnetic field of 0.2 T experiences a torque of 0.06 Nm. Calculate the magnetic moment of the magnet and find out what orientation of the magnet corresponds to stable equilibrium in magnetic field.</strong></p>



<p><strong>Given:</strong> Torque = τ = 0.06Nm, Magnetic induction
=0.2 T, angle with field = θ = 30°.</p>



<p><strong>To
find:</strong> Magnetic moment = M = ?&nbsp;θ = ?
for stable equilibrium.</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">τ
= MB sin&nbsp;θ</p>



<p>∴
M =&nbsp;τ/&nbsp;Bsin&nbsp;θ</p>



<p style="text-align:center">∴
M = 0.06/&nbsp;(0.2&nbsp;x sin 30°)&nbsp;= 0.06/&nbsp;(0.2&nbsp;x 0.5)</p>



<p style="text-align:center">∴
M = 0.6 Am<sup>2</sup></p>



<p style="text-align:center">For
stable equilibrium torque acting on magnet is zero.</p>



<p style="text-align:center">τ
= MB sin&nbsp;θ</p>



<p style="text-align:center">∴&nbsp;
0 = MB sin&nbsp;θ</p>



<p style="text-align:center">∴&nbsp;
sin&nbsp;θ = 0</p>



<p style="text-align:center">∴&nbsp;
θ = 0°</p>



<p style="text-align:center"><strong>Ans:</strong> The magnetic moment of the magnet is 0.6 Am<sup>2&nbsp;</sup>and
for stable equilibrium&nbsp;θ = 0°</p>



<p style="text-align:center">i.e.
the axis of magnet should be parallel to the magnetic field.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example &#8211; 11:</strong></p>



<p><strong>A bar magnet of moment&nbsp; 0.9 JT</strong><sup><strong>-1</strong></sup><strong> experiences a torque of 0.063&nbsp;Nm, when placed inclined at 30° in a uniform magnetic field. Find the magnetic induction of the field.</strong></p>



<p><strong>Given:</strong> Magnetic moment = M = 0.9 JT<sup>-1</sup>, angle with field
= θ = 30°, Torque =&nbsp;τ = 0.063&nbsp;Nm</p>



<p><strong>To
find:</strong> Magnetic induction = B =?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">τ
= MB sin&nbsp;θ</p>



<p style="text-align:center">∴
B =&nbsp;τ/&nbsp;Msin&nbsp;θ</p>



<p style="text-align:center">∴
B = 0.063/&nbsp;(0.9 x sin 30°)&nbsp;= 0.063/&nbsp;(0.9 x 0.5)</p>



<p style="text-align:center">∴
B = 0.14 T</p>



<p style="text-align:center"><strong>Ans:</strong> The magnetic induction is&nbsp; is 0.14 T.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example &#8211; 12:</strong></p>



<p><strong>A magnet of dipole moment 6.4 Am</strong><sup><strong>2</strong></sup><strong>&nbsp;and length 5 x 10</strong><sup><strong>-3</strong></sup><strong> m makes an angle of 60° with the magnetic field of 0.4 T. calculate the torque acting on it. Also find the pole strength of the magnet.</strong></p>



<p><strong>Given:</strong> Magnetic moment = M = 6.4 Am<sup>2</sup>,&nbsp;Magnetic induction
= B = 0.4 T, angle with field = θ = 60°, magnetic length =&nbsp;5 x 10<sup>-3</sup>
m</p>



<p><strong>To
find:</strong>&nbsp;Torque = τ =? pole strength =
m = ?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">τ
= MB sin&nbsp;θ</p>



<p style="text-align:center">∴
τ = 6.4 x 0.4x sin&nbsp;60° = 6.4 x 0.4x
0.8860 = 2.2&nbsp;Nm</p>



<p style="text-align:center">M
= m x magnetic length</p>



<p style="text-align:center">∴&nbsp;
m = M/magnetic length = 6.4/5 x 10<sup>-3&nbsp;</sup>= 1.28 x 10<sup>3</sup> Am</p>



<p style="text-align:center"><strong>Ans:</strong> The torque required is 1.28 x 10<sup>3</sup> Nm</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example &#8211; 13:</strong></p>



<p><strong>Two magnets of magnetic moments M and √3M are joined together to form a cross. The combination is suspended freely in a uniform magnetic field. In the equilibrium position the magnet of magnetic moment M makes an angle θ with the field. Determine θ.</strong></p>



<p><strong>Solution:</strong></p>



<p>The
magnet of magnetic moment M makes an angle θ with the field.</p>



<p>As
the two magnets are forming cross, the magnet of magnetic
moment&nbsp;√3M&nbsp;makes an angle (90° &#8211; θ) with the field.</p>



<p>Let
B be the magnetic strength of the external field.</p>



<p>For
equilibrium the torque acting on the two magnets must be equal.</p>



<p style="text-align:center">τ<sub>1</sub>
=&nbsp;τ<sub>2</sub></p>



<p style="text-align:center">∴&nbsp;
MB sin&nbsp;θ =&nbsp; √3MB sin (90° &#8211; θ)</p>



<p style="text-align:center">∴&nbsp;
sin&nbsp;θ =&nbsp; √3&nbsp;cos θ</p>



<p style="text-align:center">∴&nbsp;
tan&nbsp;θ =&nbsp; √3</p>



<p style="text-align:center">∴&nbsp;
θ =&nbsp; 60°</p>



<p style="text-align:center"><strong>Ans: </strong>Hence the value of&nbsp;θ is&nbsp;&nbsp;60°</p>



<h4 class="wp-block-heading"><strong>Science &gt; </strong><a rel="noreferrer noopener" href="https://thefactfactor.com/physics/" target="_blank"><strong>Physics</strong></a><strong> &gt; </strong><a rel="noreferrer noopener" href="https://thefactfactor.com/physics/magnetism/" target="_blank"><strong>Magnetism</strong></a><strong> &gt; Torque Acting on Bar Magnet in Uniform Magnetic Field</strong></h4>
<p>The post <a href="https://thefactfactor.com/facts/pure_science/physics/torque-acting-on-bar-magnet-in-uniform-magnetic-field/4792/">Torque Acting on Bar Magnet in Uniform Magnetic Field</a> appeared first on <a href="https://thefactfactor.com">The Fact Factor</a>.</p>
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		<title>Magnetic Dipole Moment of a Magnet</title>
		<link>https://thefactfactor.com/facts/pure_science/physics/magnetic-dipole-moment/4784/</link>
					<comments>https://thefactfactor.com/facts/pure_science/physics/magnetic-dipole-moment/4784/#respond</comments>
		
		<dc:creator><![CDATA[Hemant More]]></dc:creator>
		<pubDate>Mon, 11 Nov 2019 10:08:45 +0000</pubDate>
				<category><![CDATA[Physics]]></category>
		<category><![CDATA[Bar magnet]]></category>
		<category><![CDATA[Electric circuit]]></category>
		<category><![CDATA[Fictitious poles]]></category>
		<category><![CDATA[Geometric length]]></category>
		<category><![CDATA[Like poles]]></category>
		<category><![CDATA[Magnetic circuit]]></category>
		<category><![CDATA[Magnetic dipole]]></category>
		<category><![CDATA[Magnetic dipole moment]]></category>
		<category><![CDATA[Magnetic field]]></category>
		<category><![CDATA[Magnetic induction]]></category>
		<category><![CDATA[Magnetic intensity]]></category>
		<category><![CDATA[Magnetic length]]></category>
		<category><![CDATA[Magnetic poles]]></category>
		<category><![CDATA[Nort pole]]></category>
		<category><![CDATA[south pole]]></category>
		<category><![CDATA[Unlike poles]]></category>
		<guid isPermaLink="false">https://thefactfactor.com/?p=4784</guid>

					<description><![CDATA[<p>Science > Physics > Magnetism > Magnetic Dipole Moment of a Magnet In this article, we shall study the terminology of a bar magnet and the concept of the magnetic dipole moment of a magnet. Bar Magnet: A bar magnet is a rectangular parallelepiped body which exhibits magnetic properties. When a bar magnet is suspended [&#8230;]</p>
<p>The post <a href="https://thefactfactor.com/facts/pure_science/physics/magnetic-dipole-moment/4784/">Magnetic Dipole Moment of a Magnet</a> appeared first on <a href="https://thefactfactor.com">The Fact Factor</a>.</p>
]]></description>
										<content:encoded><![CDATA[
<h4 class="wp-block-heading"><strong>Science > </strong><a rel="noreferrer noopener" href="https://thefactfactor.com/physics/" target="_blank"><strong>Physics</strong></a><strong> > </strong><a rel="noreferrer noopener" href="https://thefactfactor.com/physics/magnetism/" target="_blank"><strong>Magnetism</strong></a><strong> > Magnetic Dipole Moment of a Magnet</strong></h4>



<p>In this article, we shall study the terminology of a bar magnet and the concept of the magnetic dipole moment of a magnet.</p>



<p class="has-text-color has-background has-medium-font-size has-luminous-vivid-orange-color has-very-light-gray-background-color"><strong>Bar
Magnet:</strong></p>



<p>A bar magnet is a rectangular parallelepiped body which exhibits magnetic properties. When a bar magnet is suspended in the air such that it is free to rotate about the transverse axis passing through its centre, then it is found that the bar magnet always aligns itself in the north-south direction. The end of the magnet which is pointing towards the geographical north is called north-seeking pole or simply north pole, while the end of the magnet pointing towards the geographical south is called south seeking pole or simply south pole. From the behaviour of a bar magnet, we can say that earth itself is behaving like a magnet. The magnetic north pole of the earth is at geographical south pole while the magnetic south pole of the earth is at the geographical north pole.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>&nbsp;A
Magnetic Monopole Does Not Exist:</strong></p>



<p>A bar magnet
is said to have two poles located at the two ends of the magnet. If we try to
break the bar magnet at the centre and separate the poles, new poles are formed
at the broken ends. Thus two new magnets are formed each having two opposite
poles at their ends. If the magnet is broken down into very small pieces
further each piece will be a magnet with two poles. It means it is not possible
for us to separate the poles. Thus we can say that a magnetic monopole does not
exist.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Fictitious
Poles:</strong></p>



<p>It is not possible to separate the two poles (the south pole and the north pole) by breaking the magnet into two parts. Similarly, it is not possible to locate the position of the poles of the magnet. Hence a magnetic dipole is supposed to be made up of two fictitious or imaginary poles. The position of these fictitious poles is found using a compass needle. And it is found that they are not located exactly at the ends of the magnet but slightly inside.</p>



<div class="wp-block-image"><figure class="aligncenter"><img loading="lazy" decoding="async" width="272" height="159" src="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-05.png" alt="Magnets" class="wp-image-4621"/></figure></div>



<ul class="wp-block-list"><li>Geometric Length of magnet: The length of the edge parallel to the magnetic axis is called the geometric length of the bar magnet.</li><li>Magnetic Length of Magnet: The distance between the poles of a bar magnet is called magnetic length.</li></ul>



<p>Magnetic
length of bar magnet&nbsp;× 1.2 = Geometric length of the bar magnet.</p>



<ul class="wp-block-list"><li>Axis of Magnet: The line joining the
poles of the bar magnet to called an axis of the magnet.</li></ul>



<ul class="wp-block-list"><li>Equator of Magnet: The perpendicular drawn to the magnetic axis through the centre of magnet is called the equator of the magnet.</li></ul>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Need
of Analogy of Magnetic Circuit with Electric Circuit:</strong></p>



<p>If we try to break the bar magnet at the centre and separate the poles, new poles are formed at the broken ends. It means it is not possible for us to separate the poles and study them individually hence the magnetic circuit is studied in analogy with the electrical circuit. Formulae &amp; concepts are derived from an electrical circuit and by analogy formula for a magnetic circuit is written.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Magnetic
Induction at a Point in Magnetic Field:</strong></p>



<p>The magnetic
intensity or magnetic induction at any point in the magnetic field is equal to
the number of tubes of force passing through the unit area of a small surface
element drawn at that point.</p>



<p style="text-align:center">B
=&nbsp;∅ / A</p>



<p style="text-align:center">Where B = magnetic intensity or intensity of the magnetic field </p>



<p style="text-align:center">or magnetic induction.</p>



<p style="text-align:center">∅
= Magnetic flux.&nbsp; Its unit as weber (Wb)</p>



<p style="text-align:center">A
= Area through which magnetic flux pass.</p>



<p style="text-align:center">Unit of
Magnetic induction B is Wb/m² or tesla (T)</p>



<p class="has-text-color has-background has-medium-font-size has-luminous-vivid-orange-color has-very-light-gray-background-color"><strong>&nbsp;Magnetic
Dipole: </strong></p>



<p>A magnetic
dipole can be defined as two equal and opposite magnetic poles separated by a
finite distance. A magnetic dipole consists of two equal and opposite magnetic
charges having pole strength +m &amp; -m separated by finite distance ‘2l’.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Magnetic
Dipole Moment:</strong></p>



<p>The magnetic
dipole moment is defined as the product of the pole strength and the magnetic
length of a magnet.</p>



<p style="text-align:center">M
= m × 2l</p>



<p>The magnetic
dipole moment is a vector quantity. Its direction is from -m to + m i.e. from the
south pole to the north pole. SI unit of Magnetic dipole moment is ampere.
metre²&nbsp; i.e. Am²</p>



<div class="wp-block-image"><figure class="aligncenter is-resized"><img loading="lazy" decoding="async" src="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-43.png" alt="" class="wp-image-4786" width="174" height="144"/></figure></div>



<p>A current-carrying coil behaves like a magnet.</p>



<p style="text-align:center">Magnetic dipole moment of current-carrying coil = NiA</p>



<p style="text-align:center">Where
N = Number of turns of coil</p>



<p style="text-align:center">I=
Current through the coil</p>



<p style="text-align:center">A = Area of the coil</p>



<p class="has-text-color has-background has-medium-font-size has-luminous-vivid-orange-color has-very-light-gray-background-color"><strong>Numerical Problems on Bar Magnet:</strong></p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example
&#8211; 01:</strong></p>



<p><strong>A bar magnet of geometric length 18 cm has pole strength 100 Am. Find the magnetic dipole moment of the bar magnet.</strong></p>



<p><strong>Given:</strong>&nbsp;Geometric length of bar magnet = 18 cm&nbsp;= 0.18 m,
Pole strength = m = 100 Am</p>



<p><strong>To
Find:</strong> Magnetic dipole moment = M = ?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">Magnetic
length = (5/6) x Geometric length = (5/6) x 0.18 = 0.15 cm</p>



<p style="text-align:center">M
= m x magnetic length</p>



<p style="text-align:center">∴&nbsp;&nbsp;M
= 100 x 0.15 = 15Am<sup>2</sup></p>



<p style="text-align:center"><strong>Ans:</strong> The magnetic dipole moment of bar magnet is 15 Am<sup>2</sup>.</p>



<p style="text-align:left" class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example
&#8211; 02:</strong></p>



<p><strong>A bar magnet of magnetic length 0.1 m has pole strength of 10 Am. What is the dipole moment of this magnet?</strong></p>



<p><strong>Given:</strong>&nbsp;Magnetic length of bar magnet = 0.1 m, Pole strength =
m = 10 Am</p>



<p><strong>To
Find:</strong> Magnetic dipole moment = M = ?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">M
= m x magnetic length</p>



<p style="text-align:center">∴&nbsp;&nbsp;M
= 10 x 0.1 = 1Am<sup>2</sup></p>



<p style="text-align:center"><strong>Ans:</strong> The magnetic dipole moment of bar magnet is 1 Am<sup>2</sup>.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example
&#8211; 03:</strong></p>



<p><strong>A bar magnet of the magnetic moment 5 Am</strong><sup><strong>2</strong></sup><strong> has poles 0.2 m apart. Calculate the pole strength.</strong></p>



<p><strong>Given:</strong>&nbsp;Magnetic moment = 5 Am<sup>2</sup>, magnetic length of
bar magnet = 0.2 m,</p>



<p><strong>To
Find:</strong> pole strength = m = ?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">M
= m x magnetic length</p>



<p style="text-align:center">∴
m = M/ magnetic length = 5/0.2 = 25 Am</p>



<p style="text-align:center"><strong>Ans:</strong> The pole strength of bar magnet is 25 Am.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example
&#8211; 04:</strong></p>



<p><strong>A bar magnet has pole strength 48 Am which are 0.25 m apart. What is the magnetic moment of the magnet?</strong></p>



<p><strong>Given:</strong>&nbsp;Magnetic length of bar magnet = 0.25 m, Pole strength
= m = 48 Am</p>



<p><strong>To
Find:</strong> Magnetic dipole moment = M = ?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">M
= m x magnetic length</p>



<p style="text-align:center">∴&nbsp;&nbsp;M
= 48 x 0.25 = 12Am<sup>2</sup></p>



<p style="text-align:center"><strong>Ans:</strong> The magnetic dipole moment of bar magnet is 12 Am<sup>2</sup>.</p>



<p class="has-text-color has-background has-medium-font-size has-luminous-vivid-orange-color has-very-light-gray-background-color"><strong>Problems on Magnetic Dipole Moment of Current-Carrying Coil:</strong></p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example
&#8211; 05:</strong></p>



<p>A circular
coil of 20 turns and radius 10 cm has a magnetic dipole moment of 3.142 Am<sup>2</sup>.
What is the current flowing through the coil.</p>



<p><strong>Given:</strong> Number of turns = n = 20, radius of coil = 10 cm = 0. 1 m,
magnetic dipole moment = M =&nbsp;3.142 Am<sup>2</sup>.</p>



<p><strong>To
Find:</strong> Current through the coil = i = ?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">M = n I A</p>



<p style="text-align:center"> ∴&nbsp;&nbsp; i = M/nA = M/ (n x  π r<sup>2</sup> ) </p>



<p style="text-align:center"> ∴&nbsp;&nbsp; i  =  3.142/ (20 x  3.142 x (0.1)<sup>2</sup> )  = 5 A</p>



<p style="text-align:center"><strong>Ans:</strong> The current through the coil is 5 A.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example
&#8211; 06:</strong></p>



<p><strong>A circular coil of 50 turns and 10 cm radius carries a current of 2 A. Find the magnetic moment of the coil.</strong></p>



<p><strong>Given:</strong> Number of turns = n = 50, radius of coil = 10 cm = 0. 1 m,
Current through coil = i = 2 A.</p>



<p><strong>To
Find:</strong> Magnetic dipole moment = M = ?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">M
= n i A = n i (π r<sup>2</sup>)</p>



<p style="text-align:center">∴&nbsp;&nbsp;M
=&nbsp; 50 x 2 x 3.142 x (0.1)<sup>2</sup>&nbsp;= 3.142 Am<sup>2</sup></p>



<p style="text-align:center"><strong>Ans:</strong> The magnetic dipole moment is 3.142 Am<sup>2</sup>.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example
&#8211; 07:</strong></p>



<p><strong>A circular coil has 1000 turns each of area 2 m</strong><sup><strong>2</strong></sup><strong>. If a current of 3 mA flows through the coil, find the magnetic moment of the coil.</strong></p>



<p><strong>Given:</strong> Number of turns = n = 1000, Area of coil = A =&nbsp;2 m<sup>2</sup>,
Current through coil = i = 3 mA = 3 x 10<sup>-3</sup> A</p>



<p><strong>To
Find:</strong> Magnetic dipole moment = M = ?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">M
= n i A</p>



<p style="text-align:center">∴&nbsp;&nbsp;M
=&nbsp; 1000 x 3 x 10<sup>-3&nbsp;</sup>x 2&nbsp;= 6Am<sup>2</sup></p>



<p style="text-align:center"><strong>Ans:</strong> The magnetic dipole moment is 6 Am<sup>2</sup>.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example
&#8211; 08:</strong></p>



<p><strong>A rectangular coil of length 8 cm and breadth 5 cm has 200 turns of insulated wire. Find the magnetic dipole moment of the coil. When a current of 2 A flows through it.</strong></p>



<p><strong>Given:</strong> Number of turns = n = 200, Area of coil = A =&nbsp;8 cm x 5
cm = 40 cm<sup>2</sup> = 40 x 10<sup>-4</sup> m<sup>2</sup>, Current through
coil = i = 2 A</p>



<p><strong>To
Find:</strong> Magnetic dipole moment = M = ?</p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">M
= n i A</p>



<p style="text-align:center">∴&nbsp;&nbsp;M
=&nbsp; 200 x 40 x 10<sup>-4&nbsp;</sup>x 2&nbsp;= 1.6Am<sup>2</sup></p>



<p style="text-align:center"><strong>Ans:</strong> The magnetic dipole moment is 1.6 Am<sup>2</sup>.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Example
&#8211; 09:</strong></p>



<p><strong>A steel wire of length &#8216;</strong><em><strong>l</strong></em><strong>&#8216; has a magnetic moment  M. If the wire is bent in a semicircular arc, what would its moment be?</strong></p>



<p><strong>Solution:</strong></p>



<p style="text-align:center">Let
m be the pole strength</p>



<p style="text-align:center">Now,
M = m x magnetic length</p>



<p style="text-align:center">∴&nbsp;
m = M/<em>l</em></p>



<div class="wp-block-image"><figure class="aligncenter"><img loading="lazy" decoding="async" width="300" height="192" src="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-44.png" alt="Magnetic Dipole Moment" class="wp-image-4787"/></figure></div>



<p style="text-align:center">Curved
length of semicircle =&nbsp;half circumference</p>



<p style="text-align:center">∴&nbsp;
&nbsp;<em>l</em> =&nbsp;π r</p>



<p style="text-align:center">∴
r = <em>l&nbsp;</em>/π</p>



<p style="text-align:center">Now
new magnetic dipole moment</p>



<p style="text-align:center">M
= m x new magnetic length</p>



<p style="text-align:center">∴
M = (M/<em>l</em>)x 2r =&nbsp;(M/<em>l</em>)x 2 x (<em>l&nbsp;</em>/π) = 2M/π</p>



<p style="text-align:center"><strong>Ans: </strong>New magnetic moment is 2M/π</p>



<p style="text-align:center" class="has-text-color has-medium-font-size has-vivid-cyan-blue-color"><strong><a href="https://thefactfactor.com/facts/pure_science/physics/ferromagnetic/4702/">Previous Subject: Types of Magnetic Materials</a></strong></p>



<h4 class="wp-block-heading"><strong>Science &gt; </strong><a rel="noreferrer noopener" href="https://thefactfactor.com/physics/" target="_blank"><strong>Physics</strong></a><strong> &gt; </strong><a rel="noreferrer noopener" href="https://thefactfactor.com/physics/magnetism/" target="_blank"><strong>Magnetism</strong></a><strong> &gt; Magnetic Dipole Moment of a Magnet</strong></h4>
<p>The post <a href="https://thefactfactor.com/facts/pure_science/physics/magnetic-dipole-moment/4784/">Magnetic Dipole Moment of a Magnet</a> appeared first on <a href="https://thefactfactor.com">The Fact Factor</a>.</p>
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		<title>Properties of Magnet</title>
		<link>https://thefactfactor.com/facts/pure_science/physics/properties-of-magnet/4657/</link>
					<comments>https://thefactfactor.com/facts/pure_science/physics/properties-of-magnet/4657/#respond</comments>
		
		<dc:creator><![CDATA[Hemant More]]></dc:creator>
		<pubDate>Wed, 06 Nov 2019 09:14:26 +0000</pubDate>
				<category><![CDATA[Physics]]></category>
		<category><![CDATA[Loke pols]]></category>
		<category><![CDATA[Magnet]]></category>
		<category><![CDATA[Magnetic Material]]></category>
		<category><![CDATA[Magnetic poles]]></category>
		<category><![CDATA[Magnetic strength]]></category>
		<category><![CDATA[Magnetism]]></category>
		<category><![CDATA[Non magnetic material]]></category>
		<category><![CDATA[Pole of a magnet]]></category>
		<guid isPermaLink="false">https://thefactfactor.com/?p=4657</guid>

					<description><![CDATA[<p>Science &#62; Physics &#62; Magnetism &#62; Properties of Magnet In this article, we shall see the properties of magnet and experiments to verify them Types of Material: Magnetic Materials: Materials which are attracted by magnets are called magnetic material. e.g.&#160; Iron, cobalt, nickel Nonmagnetic Materials: Materials which are not attracted by magnets are called non-magnetic [&#8230;]</p>
<p>The post <a href="https://thefactfactor.com/facts/pure_science/physics/properties-of-magnet/4657/">Properties of Magnet</a> appeared first on <a href="https://thefactfactor.com">The Fact Factor</a>.</p>
]]></description>
										<content:encoded><![CDATA[
<h4 class="wp-block-heading"><strong>Science &gt; </strong><a rel="noreferrer noopener" href="https://thefactfactor.com/physics/" target="_blank"><strong>Physics</strong></a><strong> &gt; </strong><a rel="noreferrer noopener" href="https://thefactfactor.com/physics/magnetism/" target="_blank"><strong>Magnetism</strong></a><strong> &gt; Properties of Magnet</strong></h4>



<p>In this article, we shall see the properties of magnet and experiments to verify them</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Types of Material:</strong></p>



<p><strong>Magnetic Materials: </strong>Materials
which are attracted by magnets are called magnetic material. e.g.&nbsp; Iron,
cobalt, nickel</p>



<p><strong>Nonmagnetic Materials: </strong>Materials which are not attracted by magnets are called non-magnetic material. e.g. glass, plastic, rubber.</p>



<p class="has-text-color has-background has-medium-font-size has-luminous-vivid-orange-color has-very-light-gray-background-color"><strong>Experimental Verification of Properties of Magnet</strong></p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Experiment to Find Magnetic Material:</strong></p>



<p>Bring a magnet near the material to be categorized. If the material is getting attracted towards the magnet, then the material is categorized as magnetic material. If the material is not getting attracted towards the magnet, then the material is categorized as nonmagnetic material.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Experiment to Locate Poles of a Magnet:</strong></p>



<p>Suspend a bar magnet with twistless thread to a wooden stand such that it is capable of rotating about a transverse axis passing through its centre. Thus the magnet is horizontal. Let the magnet comes to rest. When it comes to rest, the end pointing towards the geographical north is called the north pole and the end&nbsp;pointing towards the geographical south is called the south pole.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Experiment to Show That the Strength of Magnet is Located at
the Poles:</strong></p>



<p>Take some iron
filings in a dish. Place a bar magnet in it. We observe that the iron filings
stick to the magnet but cluster around the poles rather than the middle portion
of the magnet. This shows that the strength of the magnet is located at the
poles.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Experiment to Show That the Like Poles Repel and Unlike
Poles Attract:</strong></p>



<p>Suspend a bar magnet with twistless thread to a wooden stand such that it is capable of rotating about a transverse axis passing through its centre. Thus the magnet is horizontal. Let the magnet comes to rest. When it comes to rest, the end pointing towards the geographical north is called the north pole and the end pointing towards the geographical south is called the south pole.</p>



<div class="wp-block-image"><figure class="aligncenter"><img loading="lazy" decoding="async" width="353" height="169" src="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-15.png" alt="Properties of Magnet" class="wp-image-4659" srcset="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-15.png 353w, https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-15-300x144.png 300w" sizes="auto, (max-width: 353px) 100vw, 353px" /></figure></div>



<p>Now bring north pole of another magnet near the north pole of the suspended magnet. We observe that the north pole of the suspended magnet moves away from the north pole of the other magnet. This phenomenon is called the magnetic repulsion.</p>



<p>Now take away the other magnet and allow the suspended magnet to come to rest. Now&nbsp;bring south pole of another magnet near the north pole of the suspended magnet. We observe that the north pole of the suspended magnet moves towards the south pole of the other magnet. This phenomenon is called magnetic attraction. </p>



<p>Thus we can conclude that like poles repel and unlike poles attract. In this experiment, if you interchange the poles, the result will be the same.</p>



<p><strong>Note:</strong></p>



<p>If an iron rod is suspended in case of the magnet, then in both the cases the rod will get attracted towards&nbsp;the other magnet. Hence attraction is not a sure test of magnetism.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Experiment to Show That the Poles of Magnet Cannot Be
Separated:</strong></p>



<p>Take a thin bar magnet which can be cut by scissors. Mark its north pole and south pole. Cut this magnet into two halves at the centre. Put these pieces in iron filings. Iron filings get attracted to both pieces at the ends.</p>



<div class="wp-block-image"><figure class="aligncenter is-resized"><img loading="lazy" decoding="async" src="https://thefactfactor.com/wp-content/uploads/2019/11/Magnet-16.png" alt="" class="wp-image-4660" width="187" height="155"/></figure></div>



<p>Suspend these pieces with twistless thread to a wooden stand such that it is capable of rotating about a transverse axis passing through its centre. Thus the magnet is horizontal. We observe that both the pieces come to rest in the north-south direction.</p>



<p>This shows that no matter how small you cut the magnet, each piece will have both the north pole and south pole. Thus the two poles of a magnet cannot be separated from each other.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>A horizontally suspended magnet always comes to rest in the north south direction:</strong></p>



<p>The earth
itself is a giant magnet. Its magnetic North pole is near geographical South
pole. Its magnetic South pole is near geographical North pole.</p>



<p>Now, unlike poles of magnet always attract each other and like poles of magnet always repel each other. Thus the north pole of the suspended magnet gets attracted towards the magnetic south pole of the earth (geographical north). Similarly, the south pole of the suspended magnet gets attracted towards the magnetic north pole of the earth (geographical south).</p>



<p>Thus the magnet when suspended in the air such that it is free to rotate about a transverse axis passing through its centre, it always comes to rest in the north-south direction.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>If a bar magnet is suspended vertically, it does not hang in the north-south direction:</strong></p>



<p>When a bar magnet is suspended vertically it is acted upon by two forces. Magnetic force due to earth’s magnetic field and the gravitational force due to earth’s gravitational field.</p>



<p>The magnetic force tries to align the magnet in the north-south direction, while gravitational force tries to move the magnet downward. The gravitational force acting on the magnet is much stronger than the magnetic force acting on the magnet. Hence, a bar magnet when suspended vertically, it does not hang in the north-south direction.</p>



<p class="has-text-color has-medium-font-size has-vivid-red-color"><strong>Repulsion rather than attraction is the test for identifying
magnet:</strong></p>



<p>Unlike poles of the magnet always attract each other and like poles of the magnet always repel each other. Thus there are two phenomena involved: attraction and repulsion. If there is neither attraction nor repulsion due to bringing a magnet near the material, then the material is nonmagnetic. If it is getting attracted then it may be magnetic or a magnet.</p>



<p>If the material is brought near a north pole of a magnet and is getting attracted. Then there are two possibilities Firstly, the material is magnetic and itself is not a magnet and is getting attracted towards the magnet and secondly, the material is a magnet and its south pole is getting attracted towards the north pole of the magnet.</p>



<p>Now, if a material is brought near a north pole of a magnet and is getting repelled. Then it means that the material is a magnet and its north pole is brought near the north pole of the magnet. Thus, repulsion rather than attraction is the test for identifying magnet.</p>



<p>These properties of magnet are used in different practical applications.</p>



<p style="text-align:center" class="has-text-color has-medium-font-size has-vivid-cyan-blue-color"><strong><a href="https://thefactfactor.com/facts/pure_science/physics/magnets/4615/">Previous Topic: Magnets</a></strong></p>



<p style="text-align:center" class="has-text-color has-medium-font-size has-vivid-cyan-blue-color"><strong><a href="https://thefactfactor.com/facts/pure_science/physics/magnetization/4662/">Next Topic: Magnetization, Demagnetization, and Induced Magnetization</a></strong></p>



<h4 class="wp-block-heading"><strong>Science &gt; </strong><a rel="noreferrer noopener" href="https://thefactfactor.com/physics/" target="_blank"><strong>Physics</strong></a><strong> &gt; </strong><a rel="noreferrer noopener" href="https://thefactfactor.com/physics/magnetism/" target="_blank"><strong>Magnetism</strong></a><strong> &gt; Properties of Magnet</strong></h4>
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