A physicist works in a laboratory where the magnetic field is `2T`. She wears a necklace enclosing area `0.01 m^(2)` in such a way that the plane of the necklace is normal to the field and is having a resistance `R=0.01Omega`. Because of power failure, the field decays to `1T` in time `10^(-3)` seconds.
The what is the total heat produced in her necklace?`(T=tesla)`

Options

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

Answer

D

Explanation

`t = 10^(-3) s, R = 10^(-2) Omega and A = 10^(-2) m^(2)`
`e = (d phi)/(dt) = ((B_(1)-B_(2))A)/(dt)`
`e = ((2-1)xx10^(-2))/(10^(-3)) = 10 V`
`:.` The heat developed, `H = (V^2t)/R`
`:. H = (10 xx 10 xx 10^(-3))/(10^(-2)) :. H = 10 J`.