Question

A charge $+q$ is placed at origin. There are two concentric spherical surfaces; $S_1$ of radius $R$ and $S_2$ of radius $2R$. Both the surfaces have their centres at the origin. Let $\phi_1$ denote the flux through $S_1$ and $\phi_2$ the flux through $S_2$. The relation between $\phi_1$ and $\phi_2$ is

• A. $\phi_1 = 2 \phi_2$
• B. $\phi_1 = \phi_2 /2$
• C. $\phi_1 = 4\phi_2$
• D. $\phi_1 = \phi_2$

Answer 1

Answer: (D)

$\phi_1 = \phi_2$

Answer 2

According to gauss law,
$\phi = \frac{q}{\varepsilon_0}$
$\therefore \:\:\: \phi_1 = \phi_2 = \frac{q}{\varepsilon_0}$