Question

A conducting circular loop of radius $\frac{10}{\sqrt{\pi}} cm$ is placed perpendicular to a uniform magnetic field of $0.5 T$ The magnetic field is decreased to zero in $0.5 s$ at a steady rate The induced emf in the circular loop at $0.25 s$ is:

• A. $emf =1 mV$
• B. $emf =100 mV$
• C. $emf =5 mV$
• D. $emf =10 mV$

Answer 1

Answer: (D)

$emf =10 mV$

Answer 2

The correct answer is (D) : $emf=10mV$
$EMF=\frac{d\phi}{dt}=\frac{BA-0}{t}$
$A=\pi r^2=\pi(\frac{0.1^2}{\pi})=0.01$
B=0.5
$EMF=\frac{(0.5)(0.01)}{0.5}=0.01V=10mV$