A transistor has a current gain of 125 and a base current of 30 µA. What is the collector current? A. 3.75 mA B. 3.2 mA C. 0.05 mA D. 13 mA E. None of the above

The correct answer is A. 3.75 mA.

The current gain of a transistor is the ratio of the collector current to the base current. In this case, the current gain is 125, so the collector current is 125 times the base current. The base current is 30 µA, so the

Option B is incorrect because it is the base current, not the collector current.

Option C is incorrect because it is much less than the base current.

Option D is incorrect because it is much greater than the base current.

Option E is incorrect because it is not one of the possible answers.