Question

The magnetic fields through two identical rings made of copper and wood are changing at the same rate. The induced electric field in copper ring will be :

• A. more than that in the wooden ring
• B. less than that in the wooden ring
• C. finite and that in the wooden ring will be zero
• D. same as that in the wooden ring

Answer 1

The correct option is D same as that in the wooden ring

emf induced = rate of change of flux = $\frac{d(\overrightarrow{A}.\overrightarrow{B})}{dt}$. As the two rings are identical the area of both the rings are same. Hence the flux and therefore the rate of change of flux in both is the same. Therefore emf induced in both is same.
Electric field = $\frac{emf}{length}$. As both the rings are identical, their length is same.
And hence the electric field in both is the same.