Question

Four concentric spherical shell is $A,B,C$ AND $D$ has radius $a,2a,3a$ and $4a$ shell $B$ and $D$ has charge $+q$ and$-q$.The shell ${}^{\prime }{C}^{\prime }$ is earthed. Find $V_A-V_C$

• A. $\frac{kq}{2a}$
• B. $\frac{kq}{3a}$
• C. $\frac{kq}{4a}$
• D. $\frac{kq}{6a}$

Answer 1

Answer: (D)

$\frac{kq}{6a}$

$V_C=\frac{Kq}{3a}+\frac{{Kq}^1}{3a}-\frac{Kq}{4a}$

$V_C=0$

$\frac{Kq}{12a}+\frac{{Kq}^1}{3a}=0$

$q^1=-\frac{q}{4}$

$V_A=\frac{Kq}{2a}-\frac{\frac{Kq}{4}}{3a}-\frac{Kq}{4a}$

$V_A=\frac{Kq}{4a}-\frac{Kq}{12a}=\frac{Kq}{6a}$

$V_A-V_C=\frac{Kq}{6a}$