An electric dipole with dipole moment is placed in an electric field . An external agent turns the dipole slowly until its electric dipole moment becomes . The work done by the external agent is equal to:
1. 4 × 10–28 J
2. –4 × 10–28 J
3. 2.8 × 10–26 J
4. –2.8 × 10–26 J
The variation of potential with distance x from a fixed point is shown in the figure. The electric field at x =13 m is:
1. 7.5 volt/meter
2. –7.5 volt/meter
3. 5 volt/meter
4. –5 volt/meter
In the circuit diagram shown all the capacitors are in\(\mu F\). The equivalent capacitance between points, A & B is (in F):
1. 14/5
2. 7.5
3. 3/7
4. None of these
Two identical parallel plate capacitors are placed in series and connected to a constant voltage source of V0 volt. If one of the capacitors is completely immersed in a liquid with dielectric constant K, the potential difference between the plates of the other capacitor will change to:
1. \(\frac{K + 1}{K} V_{0}\)
2. \(\frac{K}{K + 1} V_{0}\)
3. \(\frac{K + 1}{2 K} V_{0}\)
4. \(\frac{2 K}{K + 1} V_{0}\)
Five equal capacitors connected in series have a resultant capacitance of . The total energy stored in these when these are connected in parallel and charged to 400 V is:
1. 1 J
2. 8 J
3. 16 J
4. 4 J
Two concentric conducting spherical shells carry charge Q each. The inner shell is earthed. The charge that flows into the earth is:
1. Q
2.
3.
4.
The equivalent capacitance between the points A and B in the given network is:
1. 25
2. 16
3. 21
4. 12
An electric dipole of moment \(\vec {p} \) is lying along a uniform electric field \(\vec{E}\). The work done in rotating the dipole by \(90^{\circ}\) is:
1. \(\sqrt{2}pE\)
2. \(\frac{pE}{2}\)
3. \(2pE\)
4. \(pE\)
Two condensers, one of capacity \(C\) and the other of capacity \(\frac{C}2\) are connected to a \(V\) volt battery, as shown in the figure.
The energy stored in the capacitors when both condensers are fully charged will be:
1. \(2CV^2\)
2. \({1 \over4}CV^2\)
3. \({3 \over4}CV^2\)
4. \({1 \over2}CV^2\)
A parallel plate air capacitor has a capacity of C, the distance of separation between plates is d and potential difference V is applied between the plates. The force of attraction between the plates of the parallel plate air capacitor is:
1.
2.
3.
4.