SATHEE: magnetism-and-matter Question 5

magnetism-and-matter Question 5

Question: Q. 4. A coil of ’ $N$ ’ turns and radius ’ $R$ ’ carries a current ’ $I$ ‘. It is unwound and rewound to make a square coil of side ’ $a$ ’ having same number of turns $(N)$ . Keeping the current ’ $I$ ’ same, find the ratio of the magnetic moments of the square coil and the circular coil. C [Delhi Comptt. I, II, III 2013]

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Solution:

Ans.

$\begin{aligned} A_{1} & = π R^{2} m_{1} & = N I A_{1} A_{2} & = a^{2} m_{2} & = N I A_{2} \frac{m_{1}}{m_{2}} & = \frac{N I A_{1}}{N I A_{2}} & = \frac{π R^{2}}{a^{2}} \frac{m_{1}}{m_{2}} & = \frac{22}{7} {(\frac{R}{a})}^{2} \end{aligned}$

[Square coil] [AI Q. 1. A rectangular coil of sides ’ $l$ ’ and ’ $b$ ’ carrying a current $I$ is subjected to a uniform magnetic field $\vec{B}$ , acting perpendicular to its plane. Obtain the expression for the torque acting on it.

U] [Delhi Comptt. I, II, III 2014]

Ans. Equivalent magnetic moment of the coil,

( $\hat{n} =$ unit vector $⊥$ to the plane of the coil)

$\begin{aligned} Torque & = \vec{M} \times \vec{B} & = I l b \hat{n} \times \vec{B} & = 0 \end{aligned}$

(as $\hat{n}$ and $\vec{B}$ are parallel or antiparallel to each other)

[CBSE Marking Scheme 2014]

Magnetism And Matter

magnetism-and-matter Question 5

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Magnetism And Matter

magnetism-and-matter Question 5

Table of Contents

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

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