Q. No.In AC (alternating current) generator, a coil of wire rotates in a magnetic field.
Which of the following would change the potential difference measured by the voltmeter in the system above?
(a)
use more turns of wire in the coil.
(b)
use thicker wire.
(c)
change the speed of rotation.
Choose the correct option from the given ones:
1.
(c) only
2.
(a), (b) and (c)
3.
(a) and (b) only
4.
(a) and (c) only
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
| Assertion (A): | When a current \(I=(3+4 \sin \omega t)\) flows in a wire, then the reading of a dc ammeter connected in series is \(4\) units. |
| Reason (R): | A dc ammeter measures only the value of the current amplitude. |
| 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. |
| Assertion (A): | A capacitor can replace the choke coils in an AC circuit. |
| Reason (R): | A capacitor can reduce the current in an AC circuit like an inductor |
In the light of the above statements choose the correct answer from the options given below:
| 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. |
A capacitor and a resistor are connected in series across the AC supply. Which of the following phasor diagrams may be correct?
| 1. |  |
2. |  |
| 3. |  |
4. |  |
| Assertion (A): | Power loss in the Admin ideal choke coil is zero. |
| Reason (R): | Ideal choke coil has zero resistance. |
In the light of the above statements choose the correct answer from the options given below:
| 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. |
In the diagram, two sinusoidal voltages of the same frequency are shown. What is the frequency and the phase relationship between the voltages?
| Frequency in Hz | Phase lead of \(N\) over \(M\) in radians | |
| 1. | \(0.4\) | \(-\pi/4\) |
| 2. | \(2.5\) | \(-\pi/2\) |
| 3. | \(2.5\) | \(+\pi/2\) |
| 4. | \(2.5\) | \(-\pi/4\) |
| 1. | \(\dfrac{V_{0}}{\sqrt{3}}\) | 2. | \(V_{0}\) |
| 3. | \(\dfrac{V_{0}}{\sqrt{2}}\) | 4. | \(\dfrac{V_{0}}{2}\) |
A series \(R, L,\) and \(C\) circuit is shown here. The source frequency \(f\) is varied, but the current is kept unchanged. Which of the curves shows changes of \(V_C\) and \(V_L\) with frequency that would be valid for the circuit under consideration?
| 1. |  |
2. |  |
| 3. |  |
4. |  |
| (A) | When the capacitor is air filled. |
| (B) | When the capacitor is mica filled. |
| 1. | \(V_A>V_B\) |
| 2. | \(V_A<V_B\) |
| 3. | \(V_A=V_B\) |
| 4. | it can't be predicted. |
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