SATHEE: magnetism-and-matter Question 6

magnetism-and-matter Question 6

Question: Q. 2. A circular coil of $N$ turns and radius $R$ carries a current $I$ . It is unwound and rewound to make another coil of radius $R / 2$ , current $I$ remaining the same. Calculate the ratio of the magnetic moments of the new coil and the original coil. A [O.D. 2012]

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Solution:

Ans. We have :

$\begin{aligned} N_{1} \cdot 2 π R & = N_{2} \cdot 2 π (R / 2) N_{2} & = 2 N_{1} \end{aligned}$

Magnetic moment of a coil, $m = N A I$

For the coil of radius ’ $R$ ‘,

$m_{1} = N I A_{1} = N I π R^{2}$

For the coil of radius $R / 2$ ,

$\begin{aligned} m_{2} = N_{2} I A_{2} = 2 N I π R^{2} / 4 = N I π R^{2} / 2 1 / 2 & \Rightarrow m_{1} : m_{2} = 1 : 2 1 / 2 \end{aligned}$

[CBSE Marking Scheme 2012]

Magnetism And Matter

magnetism-and-matter Question 6

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Magnetism And Matter

magnetism-and-matter Question 6

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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