Question
A variable condenser is permanently connected to a $100$ $V$ battery. If the capacity is changed from $2\,\mu \,F$ to $10\,\mu \,F$, then change in energy is equal to
✓
Answer
(d) $\Delta U = {U_2} - {U_1} = \frac{{{V^2}}}{2}({C_2} - {C_1})$
$ = \frac{{{{(100)}^2}}}{2}(10 - 2) \times {10^{ - 6}} = 4 \times {10^{ - 2}}\,J$
$ = \frac{{{{(100)}^2}}}{2}(10 - 2) \times {10^{ - 6}} = 4 \times {10^{ - 2}}\,J$
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