Q. No.The power factor of a good choke coil is:
1. Nearly zero
2. Exactly zero
3. Nearly one
4. Exactly one
In a series \(LCR\) circuit, resistance \(R=10~\Omega\) and the impedance \(Z=20~\Omega\).
The phase difference between the current and the voltage will be:
1. \(30^{\circ}\)
2. \(45^{\circ}\)
3. \(60^{\circ}\)
4. \(90^{\circ}\)
In the circuit shown in the figure, neglecting source resistance, the voltmeter and ammeter reading respectively will be:
1. \(0~\text{V}, 3~\text{A}\)
2. \(150~\text{V}, 3~\text{A}\)
3. \(150~\text{V}, 6~\text{A}\)
4. \(0~\text{V}, 8~\text{A}\)
An AC source of variable frequency \(f\) is connected to an \(LCR\) series circuit. Which of the following graphs represents the variation of the current \(I\) in the circuit with frequency \(f\)?
| 1. |  |
2. |  |
| 3. |  |
4. |  |
| 1. | \(0.67~\text{W}\) | 2. | \(0.78~\text{W}\) |
| 3. | \(0.89~\text{W}\) | 4. | \(0.46~\text{W}\) |
| 1. | \(5000\) | 2. | \(50\) |
| 3. | \(500\) | 4. | \(5\) |
Match List I (expression for current) with List II (rms value of current) and select the correct answer.
| List I | List II | ||
| (a) | \(I=I_0 \sin \omega t \cos \omega t\) | (i) | \(I_0\) |
| (b) | \(I=I_0 \sin \left(\omega t+\frac{\pi}{3}\right)\) | (ii) | \(I_0/\sqrt{2}\) |
| (c) | \(I_0(\sin \omega t+\cos \omega t)\) | (iii) | \(I_0e\) |
| (d) | \(I=I_0(e)\) | (iv) | \(I_0/2\sqrt{2}\) |
| A | B | C | D | |
| 1. | (iv) | (ii) | (i) | (iii) |
| 2. | (iv) | (ii) | (iii) | (i) |
| 3. | (ii) | (iv) | (iii) | (i) |
| 4. | (ii) | (iv) | (i) | (iii) |
| 1. | \(120\) V | 2. | \(220\) V |
| 3. | \(30\) V | 4. | \(90\) V |
| 1. | \(200\) V, \(50\) Hz |
| 2. | \(2\) V, \(50\) Hz |
| 3. | \(200\) V, \(500\) Hz |
| 4. | \(2\) V, \(5\) Hz |
If \(R\) and \(L\) are resistance and inductance of a choke coil and \(f\) is the frequency of current through it, then the average power of the choke coil is proportional to:
1. \(R ~\)
2. \(\frac{1}{f^2}\)
3. \(\frac{1}{L^2}\)
4. All of these
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