A uniform magnetic field is restricted within a region of radius, $r.$ The magnetic field changes with time at a rate, $\frac{d\overrightarrow{B}}{dt}$. Loop one of radius $R>r$ encloses the region, $r$ and loop two of radius, $R$ is outside the region of magnetic field as shown in the figure below. Then the emf generated is

• A

  $0$ in loop one and zero in loop two.
• B

  $-\frac{d\overrightarrow{B}}{dt}\mathrm{\pi }{r}^2$ in loop one and $-\frac{d\overrightarrow{B}}{dt}\mathrm{\pi }{r}^2$ in loop two.
• C

  $-\frac{d\overrightarrow{B}}{dt}\mathrm{\pi }{r}^2$ in loop one and infinite in loop two.
• Correct answer
  D

  $-\frac{d\overrightarrow{B}}{dt}\mathrm{\pi }{r}^2$ in loop one and zero in loop two.

Hence, the correct answer is option: 'D'.