The magnetic field perpendicular to the plane of conducting ring of radius R changes at the rate $\frac{dB}{dt}$

$\varphi =\pi r^{2}B;E=e\frac{d\varphi }{dt}=\pi r^2.\frac{dB}{dt}$

If R is the resistance of ring, the current in ring $=i=\frac{e}{R}$

Consider a small element $dl$ on the ring e.m.f induced

$=\frac{e}{2\pi r}.dl$

  Resistance of element $=dR=\left(\frac{R}{2\pi r}\right)dl$

  p.d. across element $=-idR+de$

$=-\left(\frac{e}{R}\right)\left(\frac{R}{2\pi r}\right)dl+(\frac{e}{2\pi r}.dl)=0$

$\therefore$All points of the ring are at same potential