Answer:
[tex]\frac{d\phi}{dt}=\pi r^2\frac{dB}{dt}[/tex]
Explanation:
the rate of the magnetic flux is given by,
[tex]\frac{d\phi}{dt}= \frac{d(BA)}{dt}[/tex]
where B= magnetic strength
A= area of cross section
r= radius of circle
\phi= flux
=[tex]A\frac{dB}{dt}[/tex]
=[tex]\pi r^2\frac{dB}{dt}[/tex]
