For current to flow in an NPN silicon transistor's emitter-collector path, the base must be:

Get ready for the FCC General Radiotelephone Operator License (GROL) exam. Study with flashcards and multiple choice questions, each with hints and detailed explanations. Prepare effectively for your licensing test!

Multiple Choice

For current to flow in an NPN silicon transistor's emitter-collector path, the base must be:

Forward-biasing the base-emitter junction of a silicon NPN transistor is what allows current to flow from emitter to collector. This junction acts like a diode, and for silicon devices you need about 0.6 to 0.7 volts of forward bias to turn it on. So the base must sit roughly 0.7 volts above the emitter. When this is achieved, a small base current enables a much larger current to flow from emitter to collector, thanks to current amplification. If the base is at the emitter level or below, the base-emitter junction isn’t forward biased and the transistor doesn’t conduct in the emitter-collector path. A bias of only about 0.4 volts is typically insufficient to forward-bias the junction for silicon, so little or no emitter-collector current flows.

Forward-biasing the base-emitter junction of a silicon NPN transistor is what allows current to flow from emitter to collector. This junction acts like a diode, and for silicon devices you need about 0.6 to 0.7 volts of forward bias to turn it on. So the base must sit roughly 0.7 volts above the emitter. When this is achieved, a small base current enables a much larger current to flow from emitter to collector, thanks to current amplification. If the base is at the emitter level or below, the base-emitter junction isn’t forward biased and the transistor doesn’t conduct in the emitter-collector path. A bias of only about 0.4 volts is typically insufficient to forward-bias the junction for silicon, so little or no emitter-collector current flows.

More practice questions