Final answer:
BJTs consist of three layers: emitter, base, and collector, either in p-n-p or n-p-n configuration. They operate by allowing current flow in forward bias and blocking it in reverse bias, with the base current controlling the collector current, allowing for amplification or switching.
Step-by-step explanation:
Physical Layer Structure of Bipolar Junction Transistor (BJT)
A bipolar junction transistor (BJT) is an electronic device that has three distinct layers: the emitter, the base, and the collector. The physical structure is comprised of a three-layer sandwich of p-type and n-type materials; either p-n-p or n-p-n configuration. The middle part, the base, is very thin compared to the emitter and collector layers.
Response to Bias Voltage
The response of a p-n junction to forward and reverse bias voltage is essential to the operation of BJTs. With forward bias, the junction allows current to flow, and in reverse bias, it blocks current. This semiconductor behavior is crucial for amplifying and switching.
Function in Electric Circuits
The transistor acts as a valve, controlling the large collector current (Ic) with a much smaller base current (IB). This control allows BJTs to function as amplifiers or switches in electric circuits. For example, sound causes diaphragm movements that are translated into electrical signals, which are then amplified by a BJT in audio equipment.
Applications
The functionality of BJTs is widely exploited in audio amplifiers and computers, where they amplify power, current, or voltage, and act as switches that can turn currents on and off.