Question

A circuit area $0.01m^2$ is kept inside a magnetic field which is normal to its plane. The magnetic field changes from 2T to 1 T in 1 millisecond. If the resistance of the circuit is $2\Omega$. The amount of heat evolved is:

• A. 0.05 J
• B. 50 J
• C. 0.50 J
• D. 500 J

Answer 1

The correct option is A 0.05 J

$E=\frac{d\varphi }{dt}=\frac{-d\left(bds\right)}{dt}=\frac{(2-1)0.01}{{10}^{-3}}=10v$
$I=\frac{e}{R}=\frac{10}{2}=5A\therefore Heat=I^{2}Rt$
$=5\times 5\times 2\times 0.001=0.05J$