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 coil of self-inductance L is connected in series with a bulb B and an AC source. The brightness of the bulb decreases when:
1. | Frequency of the AC source is decreased |
2. | The number of turns in the coil is reduced |
3. | A capacitance of reactance Xc=XL is included in the same circuit |
4. | An iron rod is inserted in the coil |
The output current versus time curve of a rectifier is shown in the figure.
The average value of the output current in this case will be:
1. | 0 | 2. | \(I_0 \over 2\) |
3. | \(2I_0 \over \pi\) | 4. | \(I_0\) |
The variation of the instantaneous current (I) and the instantaneous emf (E) in a circuit are shown in the figure. Which of the following statements is correct?
1. | The voltage lags behind the current by π/2. |
2. | The voltage leads the current by π/2. |
3. | The voltage and the current are in phase. |
4. | The voltage leads the current by π. |
In the circuit shown below, what will be the readings of the voltmeter and ammeter?
1. 800 V, 2 A
2. 300 V, 2 A
3. 220 V, 2.2 A
4. 100 V, 2 A
In an LCR circuit, the potential difference between the terminals of the inductance is 60 V, between the terminals of the capacitor is 30 V and that between the terminals of the resistance is 40 V. The supply voltage will be equal to:
1. 50 V
2. 70 V
3. 130 V
4. 10 V
An inductor of inductance L and resistor of resistance R are joined in series and connected by a source of frequency ω. The power dissipated in the circuit is:
1.
2.
3.
4.
In an ac circuit, a resistance of R ohm is connected in series with an inductance L. If the phase angle between voltage and current is 45°, the value of inductive reactance will be:
1. | \(\frac{R}{4}\) |
2. | \(\frac{R}{2}\) |
3. | R |
4. | Cannot be found with the given data |
L, C and R represent physical quantities inductance, capacitance and resistance respectively. The combination representing the dimension of frequency will be:
1. LC
2. (LC)–1/2
3.
4.
An alternating current of frequency ‘f’ is flowing in a circuit containing a resistance R and a choke L in series. The impedance of this circuit will be:
1. R + 2πfL
2.
3.
4.