In a transistor, the base current is about ___________ of emitter current

25%
20%
35%
5%

The correct answer is 5%.

In a transistor, the base current is typically about 5% of the emitter current. This means that a small change in the base current can cause a large change in the collector current. This is why transistors are used as amplifiers.

The other options are incorrect because they do not represent the typical ratio of base current to emitter current.

Option A: 25% is too high. The base current is typically much smaller than the emitter current.

Option B: 20% is too high. The base current is typically much smaller than the emitter current.

Option C: 35% is too high. The base current is typically much smaller than the emitter current.

Option D: 5% is correct. The base current is typically about 5% of the emitter current.