Question

For the given charge configuration consisting of charges $+q_1$ and $+q_2$ such that $q_1>q_2$, the relation between flux through two imaginary spheres $S_1$ and $S_2$ as shown in the figure will be

• A. ${\varphi }_{S_1}={\varphi }_{S_2}\ne 0$
• B. ${\varphi }_{S_1}>{\varphi }_{S_2}$
• C. ${\varphi }_{S_1}<{\varphi }_{S_2}$
• D. ${\varphi }_{S_1}={\varphi }_{S_2}=0$

Answer 1

The correct option is B ${\varphi }_{S_1}>{\varphi }_{S_2}$

The electric field lines originate from positive charges and the number of field lines originating from a charge is higher for a charge with larger magnitude.

$\because q_1>q_2$

Therefore, higher number of field lines will originate from charge $q_1$. Thus, more number of field lines which are closely spaced will intersect sphere $S_1$ as compared to sphere $S_2$ as we can see in the figure.


$\Rightarrow$ ${\varphi }_{S_1}>{\varphi }_{S_2}$

$\begin{array}{c}\text{Why this question}?\\ \text{Tip: Since the magnitude of charge}\\ \text{is known it can be easily linked with}\\ \text{the number of field lines originating}\\ \text{from the given charges, Hence}{\varphi }_{S_1}\\ \text{and}{\varphi }_{S_2}\text{can be easily compared.}\end{array}$