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A parallel plate capacitor is connected to a battery. The plates are pulled apart with uniform speed. If x is the separation between the plates, then the rate of change of electrostatic energy of the capacitor is proportional toA. `x^2`B. `x`C. `1/x`D. `1/x^2` |
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Answer» Correct Answer - D d. The capacitance of capacitor `C` is `(epsilon_(0)AV)/(x):U=(1)/(2)qV=(1)/(2)(epsilon_(0)AV^(2))/(2 x)` So, `(du)/(dt)=(1)/(2)epsilon_(0)AV^(2) (-(1)/(x^(2)))(dx)/(dt)` `=(1)/(2)epsilon_(0)AV^(2)V(-(1)/(x^(2)))` From the earlier expression, `(dU)/(dt)prop(1)/(x^(2))` |
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