The magnetic field through a single loop of wire, `12 cm` in radius and of `8.5Omega` resistance, changes with time as shown in figure. Calculate the emf in the loop as a function of time. Consider the time intervals
(a) `t = 0` to `t =2.0 s` (b) `t =2.0 s` to `t =4.0 s` (c) `t =4.0 s` to `t =6.0 s`.
The magnetic field is perpendicular to the plane of the loop.

Answer

A

Explanation

`e=(d phi)/(dt)=s ((dB)/(dt))=piR^2` (slope of` B-t`graph)
a. `e=(pi)(0.12)^2(0.5/2)=0.011V/m`
b. slope of `B-t` graph is zero. Hence `e=0`
c. slope is just opposite to the slope of part a.