MHT CET · Physics · Electrostatics
Two point charges \(+10 \mu \mathrm{C}\) and \(4 \mu \mathrm{C}\) are placed 10 cm apart in air. The work required to be done to bring them 2 cm closer is
\(\left(\frac{1}{4 \pi \epsilon_0}=9 \times 10^9 \text { SI units }\right)\)
- A \(0 \cdot 65 \mathrm{~J}\)
- B \(0 \cdot 9 \mathrm{~J}\)
- C \(1 \cdot 2 \mathrm{~J}\)
- D \(2 \cdot 3 \mathrm{~J}\)
Answer & Solution
Correct Answer
(B) \(0 \cdot 9 \mathrm{~J}\)
Step-by-step Solution
Detailed explanation
\(W = k q_1 q_2 \left(\frac{1}{r_2} - \frac{1}{r_1}\right)\) \(W = (9 \times 10^9)(10 \times 10^{-6})(4 \times 10^{-6})\left(\frac{1}{0.08} - \frac{1}{0.1}\right)\)
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