The peak voltage in a 220 V AC source is

1.  220 V

2.  about 160 V

3.  about 310 V

4.  440 V

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,

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

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-coil having some resistance is connected to an AC source. Which of the following quantities have zero average value over a cycle?

(a) current
(b) induced emf in the inductor
(c) Joule heat
(d) magnetic energy stored in the inductor

Choose the correct option 

1. (a) only

2. (b), (c)

3. (c), (d)

4. (a), (b)

The AC voltage across a resistance can be measured using 

(a) a potentiometer
(b) a hot-wire voltmeter
(c) a moving-coil galvanometer
(d) a moving-magnet galvanometer

Choose the correct option 

1. (a), (b)

2. (b) only

3. (c), (d)

4. (a), (d)