Question

A physicist works in a laboratory where the magnetic field is 2 T. She wears a necklace enclosing area $0.01m^2$ in such a way that the plane of the necklace is normal to the field and is having a resistance R $=0.01\Omega$ . 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)

• A. 10 J
• B. 20 J
• C. 30 J
• D. 40 J

Answer 1

The correct option is A 10 J

$H=\frac{V^{2}t}{R}andV=\frac{N(B_2-B_1)Acos\theta }{t}$
$V=\frac{1\times (1-2)\times 0.01\times cos{\theta }^{\circ }}{{10}^{-3}}=10V$
So, $H=\frac{(10{)}^2\times {10}^{-3}}{0.01}=10J$