Question

Three large identical conducting plates of area $A$ are closely placed parallel to each other as shown (the area $A$ is perpendicular to plane of diagram). The net charge on left, middle and right plates are $Q_{\text{L}},Q_{\text{M}}$ and $Q_{\text{R}}$ respectively. If three infinitely large parallel surfaces $S_{\text{L}},S_{\text{M}}$ and $S_{\text{R}}$ are drawn passing through middle of each plate such that surfaces are perpendicular to plane of diagram as shown, then choose the correct option (s).

• A. The net charge on left side of surface $S_{\text{L}}$ is equal to net charge on right side of surface $S_{\text{R}}$.
  
• B. The net charge on left side of surface $S_{\text{L}}$ is equal to net charge on right side of surface $S_{\text{M}}$.
• C. The net charge on left side of surface $S_{\text{L}}$ is equal to net charge on right side of surface $S_{\text{L}}$.
  
• D. The net charge on right side of surface $S_{\text{L}}$ is equal to net charge on left side of surface $S_{\text{R}}$.

Answer 1

Answer: (A), (B), (C), (D)

The net charge on right side of surface $S_{\text{L}}$ is equal to net charge on left side of surface $S_{\text{R}}$.

Since net electric field inside the metal plate is zero. Net charge on left side of $S_{\text{L}}$ is equal to net charge on the right ride of $S_{\text{L}}$. So, option (c) is correct.

Also net charge between any two dotted surfaces is zero.

So net charge between surface $S_{\text{L}}$ and surface $S_{\text{R}}$ will be zero so to make electric field zero inside the left plate, net charge on left side of surface $S_{\text{L}}$ is equal to net charge on right side of surface $S_{\text{R}}$.
Option (a) is correct.

Hence, we can conclude that options (a), (b) , (c) and (d) are the correct answers.