A generator produces a voltage that is given by V = 240 sin 120 t, where t is in seconds. The frequency and r.m.s. voltage are
1. 60 Hz and 240 V
2. 19 Hz and 120 V
3. 19 Hz and 170 V
4. 754 Hz and 70 V
The peak value of an alternating e.m.f. E is given by is 10 volts and its frequency is 50 Hz. At time , the instantaneous e.m.f. is
1. 10 V
2.
3. 5 V
4. 1 V
If a current I given by flows in an ac circuit across which an ac potential of has been applied, then the power consumption P in the circuit will be
1.
2.
3.
4. P = 0
An alternating current is given by the equation . The r.m.s. current is given by
1.
2.
3.
4.
1. | \( 0.2~\text{sec}\) | 2. | \( 0.25~\text{sec}\) |
3. | \(25 \times10^{-3}~\text{sec}\) | 4. | \(2.5 \times10^{-3}~\text{sec}\) |
Voltage and current in an ac circuit are given by and
1. Voltage leads the current by 30°
2. Current leads the voltage by 30°
3. Current leads the voltage by 60°
4. Voltage leads the current by 60°
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