InterviewSolution
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InterviewSolution
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A parallel plate air capacitor of capacitance `C` is connected to a cell of `emF V` and then disconnected from it. A dielectric slab of dielectric constant `K`, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect ?A. The potential difference between the plates decreases K timesB. The energy stored in the capacitor decreases K timesC. The change in energy is `(1)/(2)C_(0)V^(2)(K-1)`D. The change is energy is `(1)/(2)C_(0)V^(2)((1)/(K)-1)` |
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Answer» Correct Answer - D `"Initial energy, "U_(i)=(1)/(2)C_(0)V^(2)` `"Final energy, "U_(f)=(1)/(2)(KC_(0))((V)/(K))^(2)=(1)/(K)((1)/(2)C_(0)V^(2))` `"Change in energy "=U_(f)-U_(i)=(1)/(2)C_(0)V^(2)((1)/(K)-1)` Note that this change of energy is negative, i.e. there is a decrease of energy. |
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