Q. No.A parallel plate capacitor made of circular plates each of radius \(R=6.0\) cm has a capacitance \(C=100\) pF. The capacitor is connected to a \(230\) V AC supply with an (angular) frequency of \(300\) rad/s. The amplitude of \(\vec{B}\) at the point \(3\) cm from the axis between the plate is:
| 1. | \(1.12\times 10^{-11}\) T | 2. | \(2.01\times 10^{-12}\) T |
| 3. | \(1.63\times 10^{-11}\) T | 4. | \(1.01\times 10^{-12}\) T |
| Assertion (A): | Light can travel in vacuum where as sound cannot do so. |
| Reason (R): | Light is an electromagnetic wave whereas sound is a mechanical wave. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | Both (A) and (R) are False. |
| 1. | Ultraviolet rays | 2. | Radiowaves |
| 3. | Visible radiation | 4. | X-rays |
An EM wave radiates outwards from a dipole antenna, with \(E_0\), as the amplitude of its electric field vector. The electric field \(E_0\), which transports significant energy from the source falls off as:
1. \(\dfrac{1}{r^3}\)
2. \(\dfrac{1}{r^2}\)
3. \(\dfrac{1}{r}\)
4. remains 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)
(Permittivity of free space, \(\epsilon_0=8.85\times10^{-12}\) C2 N–1m –2)
1. \(2\)
2. \(4\)
3. \(6\)
4. \(8\)
Displacement current through a capacitor at a steady state is:
1. infinite
2. zero
3. \(\dfrac{\varepsilon_0d\phi_E}{dt}\)
4. \(\dfrac{\varepsilon_0d\phi_B}{dt}\)
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. \( 800~ \text{V} / \text{s} \)
2. \( 500~ \text{V} / \text{s} \)
3. \( 200~ \text{V} / \text{s} \)
4. \( 400 ~\text{V} / \text{s}\)
A parallel plate capacitor of capacitance \(20~\mu\text{F}\) is being charged by a voltage source whose potential is changing at the rate of \(3~\text{V/s}.\) The conduction current through the connecting wires, and the displacement current through the plates of the capacitor would be, respectively:
1. zero, zero
2. zero, \(60~\mu\text{A}\)
3. \(60~\mu\text{A},\) \(60~\mu\text{A}\)
4. \(60~\mu\text{A},\) zero
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