Q. No.A capacitor is charged with a battery and energy stored is U. After disconnecting the battery another capacitor of the same capacity is connected in parallel with it. The energy stored in each capacitor is:
1. U/2
2. U/4
3. 4 U
4. 2 U
Two charges q1 and q2 are placed 30 cm apart, as shown in the figure. A third charge q3 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. 8q2
2. 6q2
3. 8q1
4. 6q1
As per this diagram, a point charge \(\mathrm{+q}\) is placed at the origin \(\mathrm{O}.\) Work done in taking another point charge \(\mathrm{-Q}\) from the point \(\mathrm{A},\) coordinates \((\mathrm{0,a}),\) to another point \(\mathrm{B},\) coordinates \((\mathrm{a,0}),\) along the straight path \(\mathrm{AB}\) is:
| 1. | \( \left(\frac{-\mathrm{qQ}}{4 \pi \varepsilon_0} \frac{1}{\mathrm{a}^2}\right) \sqrt{2} \mathrm{a}\) | 2. | zero |
| 3. | \( \left(\frac{\mathrm{qQ}}{4 \pi \varepsilon_0} \frac{1}{\mathrm{a}^2}\right) \frac{1}{\sqrt{2}} \) | 4. | \( \left(\frac{\mathrm{qQ}}{4 \pi \varepsilon_0} \frac{1}{\mathrm{a}^2}\right) \sqrt{2} \mathrm{a}\) |
A network of four capacitors of capacity equal to is conducted to a battery as shown in the figure. The ratio of the charges on is:
1.
2.
3.
4.
The effective capacity of the network between terminals \(\mathrm{A}\) and \(\mathrm{B}\) is:
1. \(6~\mu\text{F}~\)
2. \(20~\mu\text{F} ~\)
3. \(3~\mu\text{F}~\)
4. \(10~\mu\text{F}\)
Eight equally charged tiny drops are combined to form a big drop. If the potential on each drop is 10 V, then the potential of the big drop will be:
| 1. | 40 V | 2. | 10 V |
| 3. | 30 V | 4. | 20 V |
A bullet of mass 2 g is having a charge of 2 µC. Through what potential difference must it be accelerated, starting from rest, to acquire a speed of 10 m/s?
1. 50 kV
2. 5 V
3. 50 V
4. 5 kV
An electric dipole has the magnitude of its charges as q and its dipole moment is p. It is placed in a uniform electric field E. If its dipole moment is along the direction of the field, the force on it and its potential energy are respectively:
| 1. | q.E and p.E |
| 2. | zero and minimum |
| 3. | q.E and maximum |
| 4. | 2q.E and minimum |
The energy and capacity of a charged parallel plate capacitor are \(E\) and \(C\) respectively. If a dielectric slab of \(E_r=6\) is inserted in it, then the energy and capacity become:
(Assuming the charge on plates remains constant)
| 1. | \(6 \mathrm E,~6 \mathrm C\) | 2. | \( \mathrm E,~ \mathrm C\) |
| 3. | \({E \over 6},~6 \mathrm C\) | 4. | \( \mathrm E,~6 \mathrm C\) |
Some charge is being given to a conductor. Then it's potential:
| 1. | is maximum at the surface. |
| 2. | is maximum at the centre. |
| 3. | remains the same throughout the conductor. |
| 4. | is maximum somewhere between the surface and the centre. |
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