| 1. | zero | 2. | \(\dfrac{-q^2}{4\pi\varepsilon_0d}\) |
| 3. | \(\dfrac{-q^2}{4\pi\varepsilon_0d}\Big(3-\dfrac{1}{\sqrt2}\Big)\) | 4. | \(\dfrac{-q^2}{4\pi\varepsilon_0d}\Big(6-\dfrac{1}{\sqrt2}\Big)\) |
| 1. | \(\dfrac{1}{4 \pi \varepsilon_{0}} \dfrac{Q}{r}\) | 2. | \(\dfrac{Q^{2}}{4 \pi \varepsilon_{0} r}\) |
| 3. | zero | 4. | \(\dfrac{Q^{2}}{2 r}\) |
| 1. | \(\dfrac{ke^{2}}{\varepsilon _{0}a}\) | 2. | \(\dfrac{3ke^{2}}{a}\) |
| 3. | \(\dfrac{3ke^{2}}{a^{2}}\) | 4. | \(\dfrac{ke^{2}}{a^{2}}\) |
| 1. | \(E\) | 2. | \(E^2\) |
| 3. | \(\dfrac{1}{E^2}\) | 4. | \(E^3\) |
Two charges and are placed 30 cm apart, as shown in the figure. A third charge is moved along the arc of a circle of radius 40 cm from C to D. The change in the potential energy of the system is , where k is:
1. 8
2. 6
3. 8
4. 6
| 1. | \(60\) ms–1 | 2. | \(75\) ms–1 |
| 3. | \(90\) ms–1 | 4. | \(100\) ms–1 |
Twenty-seven identical spherical drops of mercury are each maintained at a potential of \(10~\text{V}.\) If all these drops coalesce to form a single large spherical drop, then the potential energy of this larger drop will be how many times that of one of the smaller drops?
| 1. | \(143\) | 2. | \(243\) |
| 3. | \(348\) | 4. | \(564\) |
