NEET Solved Paper 2017 Question 12
Question: A 250-Turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of $ 85,\mu A $ and subjected to a magnetic field of strength 0.85 T. Work done for rotating the coil by $ 180^{o} $ against the torque is
Options:
A) $ 1.15,\mu J $
B) $ 9.1,\mu J $
C) $ 4.55,\mu J $
D) $ 2.3,\mu J $
Show Answer
Answer:
Correct Answer: B
Solution:
- $ W=MB(cos{\theta_1}-cos{\theta_2}) $ .
When it is rotated by angle $ 180^{o} $ then $ W=2MB $
$ W=2(NIA)B $ $ =2\times 250\times 85\times {10^{-6}}[1.25\times 2.1\times {10^{-4}}]\times 85 $ $ \times {10^{-2}} $ $ =9.1,\mu J $
