A capacitor acts as an infinite resistance for 

1.  DC

2.  AC

3.  DC as well as AC

4.  neither AC nor DC

An AC source producing emf
ε = ε₀ [cos(100 π s^–1)t + cos(500 π s^–1)t]
is connected in series with a capacitor and a resistor. The steady-state current in the circuit is found to be
i = i₁ cos [(100 π s^–1)t +ϕ₁] i₂ cos[(500 π s^–1)t + φ₂]

1.  i₁ > i₂ 

2.  i₁ = i₂ 

3.  i₁ < i₂

4.  the information is insufficient to find the relation between i₁ and i₂

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,

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