A series AC circuit has a resistance of 4 $\mathrm{\Omega }$ and an inductor of reactance 3 $\mathrm{\Omega }$. The impedance of the circuit is z₁. Now when a capacitor of reactance 6 $\mathrm{\Omega }$ is connected in series with the above combination, the impedance becomes $z_{2.}$ $\frac{{\mathrm{z}}_1}{{\mathrm{z}}_2}$ will be:

1. 1 : 1

2. 5 : 4

3. 4 : 5

4. 2 : 1

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

A resistance 'R' draws power 'P' when connected to an AC source. If an inductance is now placed in series with the resistance, such that the impedance of the circuit becomes 'Z' the power drawn will be:
$1.$ $P{\left(\frac{R}{Z}\right)}^2$
$2.$ $P\sqrt{\frac{R}{Z}}$
$3.$ $P\left(\frac{R}{Z}\right)$
$4.$ $P$

A 220 V, 50 Hz ac source is connected to an inductance of 0.2 H and a resistance of 20 ohms in series. How much current flows across the circuit?

1.  10 A

2.  5 A

3.  33.3 A

4.  3.33 A

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:

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 henry, C = 0.5 μF and R = 100 ohm in series, what is the resonance frequency?

1. 600 radian/sec

2. 600 Hz

3. 500 radian/sec

4. 500 Hz

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.

A step–down transformer transforms a supply line voltage of 2200 volt into 220 volt. The primary coil has 5000 turns. The efficiency and power transmitted by the transformer are 90% and 8 kilowatts respectively. How many turns are there in the secondary one?