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?

Choose the correct option 

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)