Published by:
CGP EDU Academic Team
Published on: September 12, 2026
Find the flux of the electric field through a spherical surface of radius R due to a charge of 8.85 x 10 –8 C at the center and another equal charge at a point 3R away from the center (Given: ε 0 = 8.85 × 10 –12 units)

Text Solution
Verified by ExpertsThe correct answer is:
A
Step 1: Understand that the electric flux through a closed surface is given by Gauss's Law, which states that the total electric flux, \(\Phi_E\), through a closed surface is equal to the net charge enclosed by that surface divided by the permittivity of free space, \(\epsilon_0\):
\(\Phi_E = \frac{Q_{enc}}{\epsilon_0}\)
Step 2: In this problem, the spherical surface of radius \(R\) encloses only the charge located at the center, which is \(Q = 8.85 \times 10^{-8} C\). The other charge is located at a distance of \(3R\) away from the center and does not contribute to the net charge enclosed.
Step 3: Plugging the known values into Gauss's Law:
\(\Phi_E = \frac{8.85 \times 10^{-8}}{8.85 \times 10^{-12}} = 10^{4} \, C/m^{2}\)
Step 4: Therefore, the electric flux through the spherical surface of radius \(R\) is:
\(\Phi_E = 10^{4}\, \text{N m}^2/C\)
Therefore, the answer is A.
\(\Phi_E = \frac{Q_{enc}}{\epsilon_0}\)
Step 2: In this problem, the spherical surface of radius \(R\) encloses only the charge located at the center, which is \(Q = 8.85 \times 10^{-8} C\). The other charge is located at a distance of \(3R\) away from the center and does not contribute to the net charge enclosed.
Step 3: Plugging the known values into Gauss's Law:
\(\Phi_E = \frac{8.85 \times 10^{-8}}{8.85 \times 10^{-12}} = 10^{4} \, C/m^{2}\)
Step 4: Therefore, the electric flux through the spherical surface of radius \(R\) is:
\(\Phi_E = 10^{4}\, \text{N m}^2/C\)
Therefore, the answer is A.
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