Q. No.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. \(R + 2\pi f L\)
2. \(\sqrt{R^{2} + 4 \pi^{2} f^{2} L^{2}}\)
3. \(\sqrt{R^{2} + L^{2}}\)
4. \(\sqrt{R^{2} + 2 \pi f L}\)
A resistance of \(300~\Omega\) and an inductance of \(\frac{1}{\pi}\) henry are connected in series to an AC voltage of \(20\) volts and a \(200\) Hz frequency. The phase angle between the voltage and current will be:
| 1. | \(\tan^{- 1} \dfrac{4}{3}\) | 2. | \(\tan^{- 1} \dfrac{3}{4}\) |
| 3. | \(\tan^{- 1} \dfrac{3}{2}\) | 4. | \(\tan^{- 1} \dfrac{2}{5}\) |
In a region of uniform magnetic induction B = 10–2 tesla, a circular coil of radius 30 cm and resistance π2 ohm is rotated about an axis that is perpendicular to the direction of B and which forms a diameter of the coil. If the coil rotates at 200 rpm the amplitude of the alternating current induced in the coil is :
(1) 4π2 mA
(2) 30 mA
(3) 6 mA
(4) 200 mA
The impedance of a circuit consists of 3 ohm resistance and 4 ohm reactance. The power factor of the circuit is :
(1) 0.4
(2) 0.6
(3) 0.8
(4) 1.0
The power factor of a good choke coil is:
(1) Nearly zero
(2) Exactly zero
(3) Nearly one
(4) Exactly one
1. \(LC\)
2. \((LC)^{\frac{-1}{2}}\)
3. \(\left(\frac{L}{C}\right)^{\frac{-1}{2}}\)
4. \(\frac{C}{L}\)
| 1. | \(\frac{R}{4}\) |
| 2. | \(\frac{R}{2}\) |
| 3. | \(R\) |
| 4. | Cannot be found with the given data |
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°
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