Question

g A circular loop of wire with radius 3 m is flat on the xy plane in a magnetic field which is pointed in the z-direction and has a magnitude of 5 μT. What is the magnitude of the induced emf in the loop if the loop shrinks to a radius of 1.5 m in 3 seconds?

Answer 1

Answer:

emf=-0.035V

Explanation:

this problem can be solved with the Lenz's law:

$emf=-\frac{\Delta \Phi_{B}}{\Delta t}$

where PhiB is the magnetic flux. In this case we have

$\Delta \Phi_{B}=B(A_1-A_2)$

due to the magnetic field is constant. A is the area of the circular loop. Hence

$\Delta \Phi_{B}=(5*10^{-3}T)(\pi(3m)^2-\pi(1.5m)^2)=0.106Tm^2$

Finally

$emf=-\frac{0.106Tm^2}{3s}=-0.035V$

HOPE THIS HELPS!!