JEE Mains · Physics · STD 12 - 1. Electric charges and fields
A certain charge \(Q\) is divided into two parts \(q\) and \((Q-q) .\) How should the charges \(Q\) and \(q\) be divided so that \(q\) and \((Q-q)\) placed at a certain distance apart experience maximum electrostatic repulsion?
- A \({Q}=\frac{{q}}{2}\)
- B \({Q}=3 {q}\)
- C \(Q=2 q\)
- D \(Q=4 q\)
Answer & Solution
Correct Answer
(C) \(Q=2 q\)
Step-by-step Solution
Detailed explanation
\(F=\frac{k Q(Q-q)}{\pi^{2}}\) \(\frac{d F}{d q}=0\) When force is maximum \(\frac{d F}{d q}=\frac{k}{L^{2}}[Q-2 q]=0\) \(\Rightarrow Q-2 q=0 \Rightarrow Q=2 q\)
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