Define the terms input resistance and current amplification factor of a transistor in CE mode.

Explanation

Input Resistance :- It is defined as the ratio of change in base-emitter voltage `(Delta V_(BE))` to the change in base current `(Delta I_B)` at constant collector-emitter voltage `(V_(CE))`
i.e., `r_i = ((Delta V_(BE))/(Delta I_B))_(v_(CE))`
Current amplification factor :- It is defined as the ratio of change in collector current `(Delta I_C)` to the change in base current (`Delta I_B)` at constant collector-Emitter `(V_(CE))` when the transistor is in active state.
i.e., `beta_(ac) = ((Delta I_C)/(Delta I_B))_(v_(CE))`