In AC (alternating current) generator, a coil of wire rotates in a magnetic field.

   
Which of the following would change the potential difference measured by the voltmeter in the system above?

(a)	use more turns of wire in the coil.
(b)	use thicker wire.
(c)	change the speed of rotation.

 

1.	(c) only
2.	(a), (b) and (c)
3.	(a) and (b) only
4.	(a) and (c) only

If R and L are resistance and inductance of a choke coil and f is the frequency of current through it, then the average power of the choke coil is proportional to:
1.  \(R ~\)
2.  \(\frac{1}{f^2}\)
3.  \(\frac{1}{L^2}\)
4.  All of these

In the light of the above statements choose the correct answer from the options given below:
 

A capacitor and a resistor are connected in series across the a.c supply. Which of the following phasor diagrams may be correct?

1.		2.
3.		4.

In the light of the above statements choose the correct answer from the options given below:
 

In the diagram, two sinusoidal voltages of the same frequency are shown. What is the frequency and the phase relationship between the voltages?
      

The r.m.s. value of the potential difference V shown in the figure is:

1. ${\mathrm{V}}_0/\sqrt{3}$

2. ${\mathrm{V}}_0$

3. ${\mathrm{V}}_0/\sqrt{2}$

4. ${\mathrm{V}}_0/2$

A series R, L, C circuit is shown here. The source frequency f is varied, but the current is kept unchanged. Which of the curves showing changes of $V_C and V_{L }$with frequency would be valid for the circuit under consideration?

1.		2.
3.		4.