Which statement describes the direction of current flow in an NPN transistor in active mode?

Which statement describes the direction of current flow in an NPN transistor in active mode?

• A. Current flows from emitter to base
• B. Current flows from base to emitter
• C. Current flows from emitter to collector
• D. Current flows from collector to emitter

Answer: (D)

In active mode, the main current path through an NPN transistor is from the collector toward the emitter. The base-emitter junction is forward biased to allow a small base current, while the base-collector junction is reverse biased to direct the majority of carriers from the collector to the emitter. The emitter current is the sum of the base and collector currents, leaving the transistor. So the dominant current flow described here is from the collector to the emitter. The base current flows into the base (forward-biased BE junction) and is much smaller than the collector current, which is why the collector-to-emitter path best captures the active-mode current direction.

In active mode, the main current path through an NPN transistor is from the collector toward the emitter. The base-emitter junction is forward biased to allow a small base current, while the base-collector junction is reverse biased to direct the majority of carriers from the collector to the emitter. The emitter current is the sum of the base and collector currents, leaving the transistor. So the dominant current flow described here is from the collector to the emitter. The base current flows into the base (forward-biased BE junction) and is much smaller than the collector current, which is why the collector-to-emitter path best captures the active-mode current direction.