An AC source is rated 220 V, 50 Hz. The average voltage is calculated in a time interval of 0.01 s. It 

1.  must be zero

2.  may be zero

3.  is never zero

4.  is (220\(\sqrt2\) ) V

A series AC circuit has a resistance of 4  Ω and a reactance of 3. Ω. The impedance of the circuit is

1.  5 Ω

2.  7 Ω

3.  12/7 Ω

4.  7/12 Ω

Transformers are used

1.  in DC circuits only

2.  in AC circuits only

3.  in both DC and AC circuits

4.  neither in DC nor in AC circuits

An alternating current is given by 

i – i₁ cos ωt + i₂ sin ωt

The rms current is given by

1.    \(\frac{i_{1}+i_{2}}{\sqrt{2}}\)

2.  \(\frac{\left|i_{1}+i_{2}\right|}{\sqrt{2}}\)

3.   \(\sqrt{\frac{i_{1}^{2}+i_{2}^{2}}{2}}\)

4.  \(\sqrt{\frac{i_{1}^{2}+i_{2}^{2}}{\sqrt{2}}}\)

An alternating current having peak value 14 A is used to heat a metal wire. To produce the same heating effect, a constant current i can be used where i is

1.  14 A

2.  about 20 A

3.  7 A

4.  about 10 A

A constant current of 2.8 A exists in a resistor. The RMS current is

1.  2.8 A

2.  about 2 A

3.  1.4 A

4.  undefined for a direct current

An inductor, a resistor and a capacitor are joined in series with an AC source. As the frequency of the source is slightly increased from a very low value, the reactance

(a) of the inductor increases
(b) of the resistor increases
(c) of the capacitor increases
(d) of the circuit increases

Choose the correct option 

1. (a) only

2. (b), (c)

3. (c), (d)

4. (a), (d)

The reactance of a circuit connected to an AC circuit is zero. It is possible that the circuit contains 

(a) an inductor and a capacitor
(b) an inductor but no capacitor
(c) a capacitor but no inductor
(d) neither an inductor nor a capacitor

Choose the correct option

1.  (a) only

2. (b), (c)

3. (c), (d)

4. (a), (d)