Assertion (A): In reverse biased p-n junction, the reverse saturation current is nearly constant if the reverse voltage is less than critical value.

Reason (R): The total reverse current is sum of reverse saturation current and surface leakage current.

Match the following:

1. If ensemble and time averages of a random process are identical, the process is ergodic.
2. If ensemble and time average of a random process are not identical, the process is ergodic.
3. An ergodic process is stationary.
4. A stationary process is necessarily ergodic.

Assertion (A): TWT uses a focussing mechanism to prevent the electron beam from spreading.

Reason (R): In a TWT the electron beam has to travel a much longer distance than in klystron.

Assertion (A): Magnetism can be explained by the theory of magnetic domains.

Reason (R): The existence of magnetic domains is evident from the Bitter powder patterns.

Assertion (A): Typical value of thermal resistance from source to sink of an SCR is about 0.3° C/W

Reason (R): Heat sinks of thyristors are generally made of aluminium.