A uniform magnetic field is restricted within a region of radius r. The magnetic field changes with time at a rate `(dB)/(dt)`. Loop 1 of radius R `gt` r encloses the region r and loop 2 of radius R is outside the region of magnetic field as shown in figure. Then, the emf generated is

Options

A. `-(dvecB)/dtpir^(2)` in loop 1 and zero in loop 2
B. Zero in loop 1 and zero in loop 2
C. `-(dvecB)/dtpir^(2)` in loop 1 and `-(dvecB)/dtpir^(2)` in loop 2
D. `-(dvecB)/dtpiR^(2)` in loop 1 and zero in loop 2

Answer

A

Explanation

`e=-(dvarphi)/dt=-d/dt{pir^(2)B}=-pir^(2)(dB)/dt` in loop 1 and zero in loop 2.