An AC voltage source is connected to a series \(LCR\) circuit. When \(L\) is removed from the circuit, the phase difference between current and voltage is \(\frac{\pi}{3}\). If \(C\) is instead removed from the circuit, the phase difference is again \(\frac{\pi}{3}\) between current and voltage. The power factor of the circuit is:
1. \(0.5\)
2. \(1.0\)
3. \(-1.0\)
4. zero
In a transformer, the number of turns in the primary and secondary coils is 410 and 1230 respectively. If the current in the primary is 6 A, then what is the current in the secondary coil?
1. | 2 A | 2. | 18 A |
3. | 12 A | 4. | 1 A |
A \(100~\Omega\) resistor is connected to a \(220~\text{V}\), \(50~\text{Hz}\) ac supply. The net power consumed over a full cycle is:
1. | \(484~\text{W}\) | 2. | \(848~\text{W}\) |
3. | \(400~\text{W}\) | 4. | \(786~\text{W}\) |
A 44 mH inductor is connected to a 220 V, 50 Hz ac supply. The RMS value of the current in the circuit is:
1. 1.0 A
2. 15 A
3. 15.92 A
4. 14.29 A
Calculate the Q-value of a series LCR circuit with L = 2.0 H, C = 32 μF and R = 10 \(\Omega\).
1. 35
2. 20
3. 15
4. 25
The variation of EMF with time for four types of generators is shown in the figures. Which amongst them can be called AC voltage?
(a) | (b) |
(c) | (d) |
1. | (a) and (d) |
2. | (a), (b), (c), and (d) |
3. | (a) and (b) |
4. | only (a) |
In an L-C-R series AC circuit, the voltage across each of the components - L, C and R is 50 V. The voltage across the L-R combination will be:
1. 50 V
2. \(50 \sqrt{2} ~V\)
3. 100 V
4. 0 V
A transistor-oscillator using a resonant circuit with an inductance L (of negligible resistance) and a capacitance C has a frequency f. If L is doubled and C is changed to 4C, the frequency will be:
1. f/4
2. 8f
3. f/(2√2)
4. f/2
An ideal resistance R, ideal inductance L, ideal capacitance C, and AC voltmeters are connected to an AC source as shown. At resonance:
1. | Reading in \(V_3\) = Reading in \(V_1\) |
2. | Reading in \(V_1\) = Reading in \(V_2\) |
3. | Reading in \(V_2\) = Reading in \(V_4\) |
4. | Reading in \(V_2\) = Reading in \(V_3\) |
An L-C-R series circuit with 100 Ω resistance is connected to an AC source of 200 V and an angular frequency of 300 rad/s. When only the capacitance is removed, the current lags behind the voltage by . When only the inductance is removed, the current leads the voltage by . Calculate the power dissipated in the L-C-R circuit.
1. 200 W
2. 400 W
3. 300 W
4. Zero