JEE Mains · Physics · STD 12 - 2. Electric potential and capacitance
A sphere of capacitance \(100\) pF is charged to a potential of \(100\) V. Another identical uncharged metal sphere is brought in contact with the charged sphere, then the change in the total energy stored on these spheres, when they touch is \(\alpha \times 10^{-7}\) J. The value of \(\alpha\) is __________. (combined capacitance of spheres is \(200\) pF)
- A \(5\)
- B \(\dfrac{5}{2}\)
- C \(\dfrac{7}{2}\)
- D \(\dfrac{9}{2}\)
Answer & Solution
Correct Answer
(B) \(\dfrac{5}{2}\)
Step-by-step Solution
Detailed explanation
Initial energy of the charged sphere is given by: \(U_i = \dfrac{1}{2} C V^2\) \(U_i = \dfrac{1}{2} \times 100 \times 10^{-12} \times (100)^2 = 5 \times 10^{-7}\) J When the identical uncharged sphere is brought in contact, the charge is shared equally and the common potential…
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