Q. No.The phase difference between the current and voltage of LCR circuit in series combination at resonance is
(1) 0
(2) π/2
(3) π
(4) –π
In a series resonant circuit, the ac voltage across resistance R, inductance L and capacitance C are 5 V, 10 V and 10 V respectively. The ac voltage applied to the circuit will be
(1) 20 V
(2) 10 V
(3) 5 V
(4) 25 V
In a series LCR circuit, resistance R = 10Ω and the impedance Z = 20Ω. The phase difference between the current and the voltage is
(1) 30°
(2) 45°
(3) 60°
(4) 90°
In the circuit shown below, the AC source has voltage \(V = 20\cos(\omega t)\) volts with \(\omega =2000\) rad/sec. The amplitude of the current is closest to:
1. \(2\) A
2. \(3.3\) A
3. \(\frac{2}{\sqrt{5}}\)
4. \(\sqrt{5}~\text{A}\)
In an ac circuit the reactance of a coil is \(\sqrt{3}\) times its resistance, the phase difference between the voltage across the coil to the current through the coil will be:
1. \(
\pi / 3
\)
2. \( \pi / 2
\)
3. \( \pi / 4
\)
4. \( \pi / 6\)
The capacity of a pure capacitor is 1 farad. In dc circuits, its effective resistance will be
(1) Zero
(2) Infinite
(3) 1 ohm
(4) 1/2 ohm
The power factor of an ac circuit having resistance (R) and inductance (L) connected in series and an angular velocity ω is
(1)
(2)
(3)
(4)
An inductor of inductance \(L\) and resistor of resistance \(R\) are joined in series and connected by a source of frequency \(\omega\). The power dissipated in the circuit is:
| 1. | \(\dfrac{\left( R^{2} +\omega^{2} L^{2} \right)}{V}\) | 2. | \(\dfrac{V^{2} R}{\left(R^{2} + \omega^{2} L^{2} \right)}\) |
| 3. | \(\dfrac{V}{\left(R^{2} + \omega^{2} L^{2}\right)}\) | 4. | \(\dfrac{\sqrt{R^{2} + \omega^{2} L^{2}}}{V^{2}}\) |
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
In a circuit, \(L, C\) and \(R\) are connected in series with an alternating voltage source of frequency \(f.\) The current leads the voltage by \(45^{\circ}\). The value of \(C\) will be:
| 1. | \(\dfrac{1}{2 \pi f \left( 2 \pi f L + R \right)}\) | 2. | \(\dfrac{1}{\pi f \left(2 \pi f L + R \right)}\) |
| 3. | \(\dfrac{1}{2 \pi f \left( 2 \pi f L - R \right)}\) | 4. | \(\dfrac{1}{\pi f \left(2 \pi f L - R \right)}\) |
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