In which of the cases shown in Fig. 6.70, will the mutual inductance of two coils be maximum, if the number of turns remains the same in each case?

 

In which of the cases shown in Fig. 6.70, will the mutual inductance of two coils be minimum, if the number of turns remains the same in each case?

The circuit arrangement given in Fig. 6.71 shows that when an a.c. passes through the coil $A$, the current starts flowing in the coil $B$. Name the underlying principle involved.

The circuit arrangement given in Fig. 6.71 shows that when an a.c. passes through the coil $A$, the current starts flowing in the coil $B$. Mention two factors on which the current produced in the coil $B$ depends.

Figure 6.72 given below shows an arrangement by which current flows through the bulb (X) connected with coil $B$, when a.c. is passed through coil $A$.

Explain the following observation:

Bulb lights up.

Figure 6.72 given below shows an arrangement by which current flows through the bulb (X) connected with coil $B$, when a.c. is passed through coil $A$.

Explain the following observation:

Bulb gets dimmer if the coil '$B$' is moved upwards.

Figure 6.72 given below shows an arrangement by which current flows through the bulb (X) connected with coil $B$, when a.c. is passed through coil $A$.

Explain the following observation:

If a copper sheet is inserted in the gap between the coils how the brightness of the bulb would change?

A coil $Q$ is connected to low voltage bulb $B$ and placed near another coil $P$ as shown in Fig. 6.74. Give reasons to explain the following observation:

The bulb '$B$' lights.