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. | \(2.5\) | \(-\pi/4\) |
Which of the following plots may represent the reactance of a series of LC combinations?
1. a
2. b
3. c
4. d
In an ac circuit \(I=100~sin~200~ \pi t.\) The time required for the current to reach its peak value will be:
1. | \(\frac{1}{100}~sec\) | 2. | \(\frac{1}{200}~sec\) |
3. | \(\frac{1}{300}~sec\) | 4. | \(\frac{1}{400}~sec\) |
The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100 V respectively in an L-C-R circuit. What is the power factor of this circuit?
1. 0.4
2. 0.5
3. 0.8
4. 1.0
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 X_{c}=X_{L} is included in the same circuit |
4. | An iron rod is inserted in the coil |
An \(AC\) voltage is applied to a resistance \(R\) and an inductor \(L\) in series. If \(R\) and the inductive reactance are both equal to \(3~ \Omega, \) then the phase difference between the applied voltage and the current in the circuit will be:
1. | \( \pi / 4\) | 2. | \( \pi / 2\) |
3. | zero | 4. | \( \pi / 6\) |
When an ac source of e.m.f. $e={E}_{0}\mathrm{sin}(100$ $t)$ is connected across a circuit, the phase difference between the e.m.f. e and the current i in the circuit is observed to be \(\frac{\pi}{4}\) as shown in the diagram. If the circuit consists only of RC or LC in series, then what is the relationship between the two elements?
1. | \(R=1 k \Omega, C=10 \mu F\) |
2. | \(R=1 k \Omega, C=1 \mu F\) |
3. | \(R=1 k \Omega, L=10 \ H\) |
4. | \(R=1 k \Omega, L=1 \ H\) |
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. | \(I_0\) |
A constant voltage at different frequencies is applied across a capacitance C as shown in the figure.
Which of the following graphs accurately illustrates how current varies with frequency?
1. | 2. | ||
3. | 4. |
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. |