Question

The magnitude of electric field E in the angular region of a charged cylindrical capacitor :

• A. is same throughout
• B. is higher near the outer cylinder than near the inner cylinder
• C. varies as $\frac{1}{r^2}$, where r is the distance from the axis
• D. varies as $\frac{1}{r}$, where r is the distance from the axis

Answer 1

Answer: (D)

varies as $\frac{1}{r}$, where r is the distance from the axis

$E=\frac{q}{2\pi {\epsilon }_{0}rl}$
$=\frac{q}{2\pi {\epsilon }_{0}rl}\propto \frac{1}{r}$
i.e. varies as 1/r where, r is the distance from the axis.