Magnetic Effects Of Current Question 168
Question: A circular coil of radius 4 cm has 50 turns. In this coil a current of 2 A is flowing. It is placed in a magnetic field of 0.1 $ weber/m^{2} $ . The amount of work done in rotating it through $ 180{}^\circ $ from its equilibrium position will be [CPMT 1977]
Options:
A) 0.1 J
B) 0.2 J
C) 0.4 J
D) 0.8 J
Show Answer
Answer:
Correct Answer: A
Solution:
The magnetic moment of current carrying loop $ M=niA=ni,(\pi r^{2}) $ Hence the work done in rotating it through 180° $ W=MB,(1-\cos \theta )=2MB $ $ =2(ni\pi r^{2})B $ $ =2\times (50\times 2\times 3.14\times 16\times {{10}^{-4}})\times 0.1=0.1J $
BETA
