For common emitter transistor amplifier the Audio Signal Voltage across the collector resistance of 2 kΩ is 2 V. Given that the current amplification factor of the transistor is 100, the base current is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 10 μA
The voltage across the collector resistance gives the collector current, and the current amplification factor \( \beta = I_c/I_b \) then gives the base current.
\( \displaystyle I_c = \frac{V_c}{R_c} = \frac{2\,\mathrm{V}}{2\times10^{3}\,\Omega} = 1\times10^{-3}\,\mathrm{A} = 1\,\mathrm{mA} \)
\( \displaystyle I_b = \frac{I_c}{\beta} = \frac{1\,\mathrm{mA}}{100} = 10\,\mu\mathrm{A} \)
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), and it also appears to be out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Exercises – …
