How Does a Bjt Amplify Current?

The small current travels from the voltage source into the base of the transistor. A current at the base turns on the transistor. The current is then amplified and travels from the emitter of the transistor to the collector. The amplified current is large enough to turn on and light the LED.

Why does BJT amplify current?

Voltage drop across resistors only happens when there is current flowing. No current so no voltage drop across the collector load resistor. When base bias is applied current flows, base to emitter (very small) and collector to emitter, significant. The transistor amplifies the base current.

Does BJT amplify current or voltage?

Transistor (BJT) is amplifying current if biased appropriately. But since current and voltage are tightly related, a voltage amplifier can be built around it.