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. The power consumption is:

1. 20 W

2. 40 W

3. 1000 W

4. 0 

A 100 Ω resistor is connected to a 220 V, 50 Hz ac supply. The net power consumed over a full cycle is:

1. 484 W

2. 848 W

3. 400 W

4. 786 W

A coil of inductive reactance of 31 Ω has a resistance of 8 Ω. It is placed in series with a condenser of capacitive reactance 25 Ω. The combination is connected to an a.c. source of 110 V. The power factor of the circuit is:

1. 0.56

2. 0.64

3. 0.80

4. 0.33

The power factor of the given circuit is:
           
$$\begin{gathered} 1. \frac{1}{2} \\ 2. \frac{1}{\sqrt{2}} \\ 3. \frac{\sqrt{3}}{2} \\ 4. 0 \end{gathered}$$

The power factor of a series LCR circuit in resonance condition is:

$$\begin{gathered} 1. zero \\ 2. \frac{1}{2} \\ 3. \frac{1}{\sqrt{2}} \\ 4. 1 \end{gathered}$$

The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100 V respectively in an L-C-R circuit. What is the power factor of this circuit?

1. 0.4             

2. 0.5

3. 0.8             

4. 1.0

An inductor of inductance L and resistor of resistance R are joined in series and connected by a source of frequency ω. The power dissipated in the circuit is:

1. $\frac{(R^2+{\omega }^2{L}^2)}{V}$

2. $\frac{V^{2}R}{(R^2+{\omega }^2{L}^2)}$

3. $\frac{V}{(R^2+{\omega }^2{L}^2)}$

4. $\frac{\sqrt{R^2+{\omega }^2{L}^2}}{V^2}$

In a series LCR circuit, the current through the ac source is 2 A. If resistor R has a resistance of 10 Ω, the average power dissipated in the circuit is:

1. 20 W

2. 30 W

3. 10 W

4. 40 W

What is the average power dissipated in the ac circuit if current i = 100sin100t A and V=100sin(100t+π/3) volts?

1. 2500 W

2. 250 W

3. 5000 W

4. 4000 W

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