An AC source is rated \(220~\mathrm{V}\), \(50~\mathrm{Hz}\). The average voltage is calculated in a time interval of \(0.01~\mathrm{s}\). It,

1.	must be zero
2.	may be zero
3.	is never zero
4.	is \(220\sqrt{2}\) 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 
\(i=i_1 \cos \omega t+i_2 \sin \omega t\)
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 a peak value \(14~\text A\) is used to heat a metal wire. To produce the same heating effect, a constant current \(i\) can be used, where the value of \(i\) is:
1. \(14~\text A\) 
2. about \(20~\text A\) 
3. \(7~\text A\) 
4. about \(10~\text A\) 

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

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)

In an AC series circuit, the instantaneous current is zero when the instantaneous voltage is maximum. Connected to the source may be a:

Choose the correct option: