Electric Potential - NEET Physics Questions
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Electric Potential

Practice Questions:
Question 31: easy

Two charged spherical conductors of radius \(R_1\) and \(R_2\) are connected by a wire. Then the ratio of final surface charge densities of the spheres \(\sigma_1 / \sigma_2\) is

1. \(\frac{R_1^2}{R_2^2}\)
2. \(\frac{R_1}{R_2}\)
3. \(\frac{R_2}{R_1}\)
4. \(\sqrt{\frac{R_1}{R_2}}\)
View Answer

When connected, their electric potentials become equal, i.e., \(V_1 = V_2\). Since \(V = \frac{\sigma R}{\varepsilon_0}\), we get \(\sigma_1 R_1 = \sigma_2 R_2\), which gives \(\frac{\sigma_1}{\sigma_2} = \frac{R_2}{R_1}\).

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Question 32: easy

Twenty seven drops of same size are charged at \(220\text{ V}\) each. They combine to form a bigger drop. Calculate the potential of the bigger drop.

1. 1980 V
2. 660 V
3. 1320 V
4. 1520 V
View Answer

By volume conservation, \(R = N^{1/3} r = 27^{1/3} r = 3r\). The total charge of the combined drop is \(Q = 27q\). The potential of the bigger drop is \(V' = \frac{kQ}{R} = \frac{k(27q)}{3r} = 9 V = 9 \times 220 = 1980\text{ V}\).

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