In an n-p-n common emitter (CE) transistor the collector current changes from 5 mA to 16 mA for the change in base current from 100 μ A and 200 μ A, respectively. The current gain of transistor is __________.

Solution

Physics sir · 3 steps

Current gain here means the ratio of the changes: change in collector current over change in base current.

1. Which gain. In the common emitter setup, the base current is the input and the collector current is the output. The current gain β is how much the collector current changes for a given change in the base current.

   β = (Δ I_C)/(Δ I_B)

2. Find the changes. Δ I_C = 16 - 5 = 11 mA. Δ I_B = 200 - 100 = 100 μA = 0.1 mA.
3. So. β = (11 mA)/(0.1 mA) = 110, which is option (d).

The idea to keep. When a question gives two pairs of readings, take differences before dividing. Also put both currents in the same unit, since μA and mA differ by a factor of 1000.

Answer from the NTA final answer key. Solution by PrepWiser.