In the given circuit a voltmeter V is connected across the lamp L. What changes would occur at lamp L and the voltmeter V if the resistance R is reduced in value? Give reason for your answer.
Solution
The circuit is an n-p-n transistor with the lamp in the collector branch. Reducing R raises the base current, which increases the forward bias of the emitter-base junction. A larger base current produces a proportionally larger collector current, so the lamp glows brighter and the voltmeter across it reads higher. Smaller R⇒larger IC⇒brighter lamp, higher voltmeter reading.
