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 \(R=10~\Omega\) and the impedance \(Z=20~\Omega\). The phase difference between the current and the voltage will be:

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 the figure, neglecting source resistance, the voltmeter and ammeter reading respectively will be:

1. 0 V, 3 A
2. 150 V, 3 A
3. 150 V, 6 A
4. 0 V, 8 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.

Which of the following plots may represent the reactance of a series LC combination 

(1) a

(2) b

(3) c

(4) d

In an ac circuit, I = 100 sin 200 $\mathrm{\pi t}$. The time required for the current to achieve its peak value will be

1. $\frac{1}{100}\sec$

2. $\frac{1}{200}\sec$

3. $\frac{1}{300}\sec$

4. $\frac{1}{400}\sec$