Q. No.A compass needle is placed in the gap of a parallel plate capacitor. The capacitor is connected to a battery through a resistance. The compass needle:
| 1. | does not deflect. |
| 2. | deflects for a very short time and then comes back to the original position. |
| 3. | deflects and remains deflected as long as the battery is connected. |
| 4. | deflects and gradually comes to the original position in a time which is large compared to the time constant. |
Displacement current goes through the gap between the plates of a capacitor when the charge of the capacitor:
| a. | increases |
| b. | decreases |
| c. | does not change |
| d. | is zero |
Choose the correct option:
| 1. | (a), (b) |
| 2. | (b), (c) |
| 3. | only (c) |
| 4. | (a), (d) |
A capacitor of capacitance \(C\) is connected across an AC source of voltage \(V\), given by;
\(V=V_0 \sin \omega t\)
The displacement current between the plates of the capacitor would then be given by:
1. \( I_d=\frac{V_0}{\omega C} \sin \omega t \)
2. \( I_d=V_0 \omega C \sin \omega t \)
3. \( I_d=V_0 \omega C \cos \omega t \)
4. \( I_d=\frac{V_0}{\omega C} \cos \omega t\)
1. \( 800 \mathrm{~V} / \mathrm{s} \)
2. \( 500 \mathrm{~V} / \mathrm{s} \)
3. \( 200 \mathrm{~V} / \mathrm{s} \)
4. \( 400 \mathrm{~V} / \mathrm{s}\)
| (A) | a varying sinusoidal current flowing through a capacitor |
| (B) | an electric dipole, whose size (and magnitude) is oscillating with time |
| (C) | a steady current flowing through a toroid |
| 1. | only (A) |
| 2. | only (B) |
| 3. | only (A) & (B) |
| 4. | (A), (B), (C) |
| Statement I: | Charged particles which undergo acceleration or deceleration radiate their energy away. |
| Statement II: | Therefore, charged particles moving in circular paths in a uniform magnetic field should also radiate their energy. |
| 1. | Statement I is true, Statement II is true and Statement I implies Statement II. |
| 2. | Statement I is true, Statement II is true and Statement I does not imply Statement II. |
| 3. | Statement I is true, Statement II is false. |
| 4. | Statement I is false, Statement II is true. |
Out of the following options which one can be used to produce a propagating electromagnetic wave?
| 1. | a stationary charge |
| 2. | a charge-less particle |
| 3. | an accelerating charge |
| 4. | a charge moving at constant velocity |
Assume a bulb of efficiency \(2.5\%\) as a point source. The peak values of the electric field and magnetic field produced by the radiation coming from a \(100~\mathrm{W}\) bulb at a distance of \(3~\mathrm{m}\) are respectively:
| 1. | \( 2.5 \mathrm{~V} / \mathrm{m}, ~2.2 \times 10^{-8} \mathrm{~T} \) |
| 2. | \( 3.6 \mathrm{~V} / \mathrm{m},~ 3.6 \mathrm{~T} \) |
| 3. | \( 4.07 \mathrm{~V} / \mathrm{m},~ 1.4 \times 10^{-8} \mathrm{~T} \) |
| 4. | \( 4.2 \mathrm{~V} / \mathrm{m}, ~3.4 \times 10^{-6} \mathrm{~T}\) |
The magnetic field in a plane electromagnetic wave is given by \(\mathrm{B}=\left(2 \times 10^{-7}\right) \mathrm{T} \sin \left(0.5 \times 10^3 \mathrm{x}+1.5 \times 10^{11} \mathrm{t}\right )\). The wavelength and frequency of the wave are respectively:
| 1. | \( 2.16 \mathrm{~cm}, 24.1 \mathrm{~GHz} \) |
| 2. | \( 0.29 \mathrm{~cm}, 13.7 \mathrm{~GHz} \) |
| 3. | \( 3.23 \mathrm{~cm}, 20.0 \mathrm{~GHz} \) |
| 4. | \( 1.26 \mathrm{~cm}, 23.9 \mathrm{~GHz}\) |
The maximum value of the electric field in the wave is:
1. \(E_0 \over \sqrt 2\)
2. \(E_o\)
3. \(\sqrt 2 E_0\)
4. \(\sqrt 3 E_0\)
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