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. |
(a) | use more turns of wire in the coil. |
(b) | use thicker wire. |
(c) | change the speed of rotation. |
1. | (c) only |
2. | (a), (b) and (c) |
3. | (a) and (b) only |
4. | (a) and (c) only |
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. |
1. | \(\dfrac{V_{0}}{\sqrt{3}}\) | 2. | \(V_{0}\) |
3. | \(\dfrac{V_{0}}{\sqrt{2}}\) | 4. | \(\dfrac{V_{0}}{2}\) |
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. | \(2.5\) | \(-\pi/4\) |
A series R, L, C circuit is shown here. The source frequency f is varied, but the current is kept unchanged. Which of the curves showing changes of with frequency 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. |