Physics

Problem

The magnetic field in a region is radial and varies with the distance

r

from a fixed point

O

according to

B(r)=B_0\dfrac{r}{R}

for

0\le r\le R

, where

B_0

and

R

are constants. The field is everywhere perpendicular to a flat circular surface of radius

R

centred at

O

. The total magnetic flux through the surface is a)

\dfrac{\pi B_0 R^{2}}{2}

\dfrac{2\pi B_0 R^{2}}{3}

\pi B_0 R^{2}

\dfrac{\pi B_0 R^{2}}{3}