Magnetic field B in a cylindrical region of radius r varies according to the law `B = B_(0)t` as shown in the figure. A fixed conducting loop ABCDA of resistance R is lying in the region as show . The current flowing through the loop is

Options

A. `(pia^(2)B_(0))/(12R)`
B. `(pi(r^(2)-a^(2))B_(0))/(12R)`
C. `(pi(b^(2) - a^(2))B_(0))/(12R)`
D. none of the above

Answer

B

Explanation

`e=(dphi)/(dt)=((r^(2)-a^(2)))/(2)(pi)/(6)(dB)/(dt)`
`:. i = ((r^(2)-a^(2))piB_(0))/(12R)`