In an ac circuit, the current is given by $i=5\sin \left(100t-\frac{{\displaystyle \pi }}{{\displaystyle 2}}\right)$ and the ac potential is V = 200 sin(100t) volt. Then the power consumption is :

1. 20 watts

2. 40 watts

3. 1000 watts

4. 0 watt

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

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 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°

The power factor of an ac circuit having resistance (R) and inductance (L) connected in series and an angular velocity ω is 

1. $R/\omega L$

2. $R/{(R^2+{\omega }^2{L}^2)}^{1/2}$

3. $\omega L/R$

4. $R/{(R^2-{\omega }^2{L}^2)}^{1/2}$

In an LR-circuit, the inductive reactance is equal to the resistance R of the circuit. An e.m.f. $E=E_0\cos \left(\omega t\right)$ applied to the circuit. The power consumed in the circuit is:

1. $\frac{E_0^2}{R}$

2. $\frac{E_0^2}{2R}$

3. $\frac{E_0^2}{4R}$

4. $\frac{E_0^2}{8R}$

In the circuit shown in figure neglecting source resistance the voltmeter and ammeter reading will respectively, will be 

1. 0V, 3A

2. 150V, 3A

3. 150V, 6A

4. 0V, 8A

An ac source of variable frequency f is connected to an LCR series circuit. Which one of the graphs in the figure represents the variation of the current I in the circuit with frequency f :

1. 

2. 

3. 

4.