Q. No.A resistance of \(20~ \Omega\) is connected to a source of an alternating potential, \(V=220\sin(100 \pi t).\) The time taken by the current to change from its peak value to its rms value will be:
1.
\( 0.2~\text{sec}\)
2.
\( 0.25~\text{sec}\)
3.
\(25 \times10^{-3}~\text{sec}\)
4.
\(2.5 \times10^{-3}~\text{sec}\)
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
In a LCR circuit having L = 8.0 henry, C = 0.5 μF and R = 100 ohm in series. The resonance frequency in radian per second is
(1) 600 radian/second
(2) 600 Hz
(3) 500 radian/second
(4) 500 Hz
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
© 2024 GoodEd Technologies Pvt. Ltd.