Electro Magnetic Induction And Alternating Currents Question 326
Question: A physicist works in a laboratory where the magnetic field is 2 T. She wears a necklace enclosing area 0.01 m2 in such a way that the plane of the necklace is normal to the field and is having a resistance R = 0.01 W. Because of power failure, the field decays to 1 T in time 10?3 seconds. Then what is the total heat produced in her necklace ? (T = Tesla) [Orissa JEE 2002]
Options:
A) 10 J
B) 20 J
C) 30 J
D) 40 J
Show Answer
Answer:
Correct Answer: A
Solution:
$ H=\frac{V^{2}t}{R},and $
$ V=\frac{N(B_{2}-B_{1})A\cos \theta }{t} $
$ V=\frac{1\times (1-2)\times 0.01\times \cos 0^{o}}{{{10}^{-3}}}=10\ V $
So, $ H=\frac{{{(10)}^{2}}\times {{10}^{-3}}}{0.01}=10\ J $
