(i) Identify the part of the electromagnetic spectrum which is:

(a) suitable for radar system used in aircraft navigation,

(b) produced by bombarding a metal target by high-speed electrons.

ii) Why does a galvanometer show a momentary deflection at the time of charging or discharging a capacitor ? Write the necessary expression to explain this observation.

i) a) Microwaves are suitable for radar system used in aircraft navigation.
b) X-rays are produced by bombarding a metal target with high-speed electrons.
ii) A capacitor is connected to the battery. So, electrons start moving towards the plate connected to the negative terminal of the battery and electrons leave from the plate connected to the positive terminal of the battery.
Transfer of electrons takes place until the potential of the capacitor becomes equal to that of the battery. The whole process happens very quickly, and the charging current produces deflection.
The reverse process is repeated at the time of discharging a capacitor and again galvanometer shows a momentary deflection.
Galvanometer acts as a resistance and the circuit behaves like a R-C circuit, having time constant equal to RC.
Therefore, the required expression is given by,