Question

When the base current in a transistor is changed from 30µA to 80µA, the collector current is changed from 1.0 mA to 3.5 mA. Find the current gain β.

Answer 1

Given:
Change in the base current, \[\delta I_b  = (80 - 30)  \mu \text{A}\]

Change in the collector current, \[\delta I_c  = (3 . 5 - 1)  \] mA

Base current gain = Rate of change of collector current with respect to base current
Thus,

\[\beta = \left( \frac{\delta l_c}{\delta l_b} \right)  \text{at  constant   V}_{cc} \] 

\[ \Rightarrow \beta = \frac{2 . 5 \times {10}^{- 3}}{50 \times {10}^{- 6}}\] 

\[ \Rightarrow \beta = \frac{250}{50} = 50\]