When a step-down transformer is connected to a 2400 volt line, the output load receives 80 amps of current. The ratio of the turns in the primary and secondary coils is 20:1. If transformer efficiency is 100%, then the current flowing in the primary coil will be:
1. | 1600 A | 2. | 20 A |
3. | 4 A | 4. | 1.5 A |
1. | \(60\) Hz and \(240\) V |
2. | \(19\) Hz and \(120\) V |
3. | \(19\) Hz and \(170\) V |
4. | \(754\) Hz and \(70\) V |
In an ac circuit, the current is given by \(i=5\sin(100t-\frac{\pi}{2})\) and the ac potential is V = 200 sin(100t) volt. The power consumption is:
1. 20 W
2. 40 W
3. 1000 W
4. 0
In an \(LCR\) circuit having \(L = 8.0~\text{H}\), \(C= 0.5~\mu\text{F}\) and \(R = 100~\Omega\) in series, what is the resonance frequency?
1. \(600\) radian/sec
2. \(600\) Hz
3. \(500\) radian/sec
4. \(500\) Hz
A circuit consists of 3 ohms of resistance and 4 ohms of 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
In a series \(LCR\) circuit, resistance \(R=10~\Omega\) and the impedance \(Z=20~\Omega\).
The phase difference between the current and the voltage will be:
1. \(30^{\circ}\)
2. \(45^{\circ}\)
3. \(60^{\circ}\)
4. \(90^{\circ}\)
In the circuit shown in the figure, neglecting source resistance, the voltmeter and ammeter reading respectively will be:
1. \(0~\text{V}, 3~\text{A}\)
2. \(150~\text{V}, 3~\text{A}\)
3. \(150~\text{V}, 6~\text{A}\)
4. \(0~\text{V}, 8~\text{A}\)
An ac source of variable frequency \(f\) is connected to an \(LCR\) series circuit. Which of the following graphs represents the variation of the current \(I\) in the circuit with frequency \(f\)?
1. | 2. | ||
3. | 4. |
An inductor of \(20~\mathrm{mH},\) a capacitor of \(50~ \mu F,\) and a resistor of \(40~ \Omega\) are connected in series across a source of emf of \(V=10sin(340t).\) What will be the power loss in the AC circuit?
1. | \(0.67~ \mathrm{W}\) | 2. | \(0.78~ \mathrm{W}\) |
3. | \(0.89~ \mathrm{W}\) | 4. | \(0.46~ \mathrm{W}\) |