A variable condenser is permanently connected to a \(100 \mathrm{~V}\) battery. If capacitor is changed from \(2 \mu \mathrm{F}\) to \(10 \mu \mathrm{F}\). then energy changes is equal to (A) \(2 \times 10^{-2} \mathrm{~J}\) (B) \(2.5 \times 10^{-2} \mathrm{~J}\) (C) \(6.5 \times 10^{-2} \mathrm{~J}\) (D) \(4 \times 10^{-2} \mathrm{~J}\)

Short Answer

Expert verified
The change in energy when the capacitor is changed from $2 \mu \mathrm{F}$ to $10 \mu \mathrm{F}$ is \(\boldsymbol{4 \times 10^{-2} \mathrm{~J}}\).

Step by step solution

01

Calculate the energy for the first capacitor

The energy stored in a capacitor can be calculated using the following formula: \[E = \frac{1}{2}CV^2\] where C is the capacitance, and V is the voltage across the capacitor. For the first capacitor with a capacitance of 2 μF, the energy stored can be calculated as: \(E_1 = \frac{1}{2}(2\times10^{-6}\,\mathrm{F})(100\,\mathrm{V})^2\)
02

Calculate the energy for the second capacitor

Similarly, for the second capacitor with a capacitance of 10 μF, the energy stored can be calculated using the same formula: \(E_2 = \frac{1}{2}(10\times10^{-6}\,\mathrm{F})(100\,\mathrm{V})^2\)
03

Calculate the change in energy

Now, we will calculate the change in energy by finding the difference between the two energy values: ΔE = E₂ - E₁
04

Substitute the values and find the answer

Substitute the values of E₁ and E₂ in the formula, and calculate the change in energy: ΔE = \(\frac{1}{2}(10\times10^{-6}\,\mathrm{F})(100\,\mathrm{V})^2\) - \(\frac{1}{2}(2\times10^{-6}\,\mathrm{F})(100\,\mathrm{V})^2\) ΔE = \(4\times10^{-2}\,\mathrm{J}\) Hence, the change in energy is \(\boldsymbol{4 \times 10^{-2} \mathrm{~J}}\), which corresponds to option (D).

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