Question

Four point charges $q_1, q_2, q_3$ and $q_4$ are as shown in figure. The flux over the shown Gaussian surface depends only on charges $q_1$ and $q_2$. Electric field at all points on Gaussian surface depends only on charges $q_1$ and $q_2$.

• A. If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
• B. If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
• C. If Assertion is correct but Reason is incorrect.
• D. If both the Assertion and Reason are incorrect.

Answer 1

Answer: (C)

If Assertion is correct but Reason is incorrect.

Answer 2

By Gauss Law, total flux will depend only on enclosed charges, i.e. $q _{1}$ and $q _{2}$ but flux at each point will depend on all charges. $$ \phi=\frac{ q _{\text {enclosed }}}{\epsilon} $$ Electric field depends on all $q _{1}, q _{2}, q _{3}$ and $q _{4}$,