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Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsElectrostatic Potential and Capacitance1 Mark
Question
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, and R is also false.
Assertion (A): A capacitor is connected to a battery. If we move its plate further apart, work will be done against the electrostatic attraction between the plates, and the energy of the capacitor gets decreased.
Reason (R): The energy stored in capacitor is dissipated in the form of heat energy.
✓

Answer

  1. Both A and R are true, but R is not the correct explanation of A.
Explanation:

When the plates of a capacitor are moved further apart, the capacitance gets decreased. As battery remains connected, hence charge q( = CV) on the plates is decreased, and energy $\text{U}=\Big[\frac{1}{2}\text{CV}^2\Big]$ also decreases. Some charge from the plates flows to the battery i.e. some energy of capacitor is transferred to the battery. Work done against electrostatic attraction between plates is used in the transference of energy and is dissipated in the form of heat energy in connection wires.

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