[amp_mcq option1=”Forward-biased” option2=”Reverse-biased” option3=”Nonconducting” option4=”Operating in the breakdown region E. None of the above” correct=”option1″]
The correct answer is A. Forward-biased.
A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor’s terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.
A transistor can be thought of as two semiconductor diodes connected back-to-back with a thin layer of semiconductor material between them. The two diodes are called the emitter-base junction and the collector-base junction. The thin layer of semiconductor material is called the base.
When a small voltage is applied to the base-emitter junction, it causes a large current to flow through the collector-emitter junction. This is because the base-emitter junction is forward-biased, which means that the positive terminal of the voltage source is connected to the base and the negative terminal is connected to the emitter. This forward bias causes the electrons in the base region to be injected into the collector region. The electrons in the collector region then flow out of the collector terminal and into the external circuit.
The amount of current that flows through the collector-emitter junction is controlled by the amount of current that flows through the base-emitter junction. This is because the base-emitter junction is a very small junction, and a small change in the current through it can cause a large change in the current through the collector-emitter junction.
Transistors are used in a wide variety of electronic devices, including amplifiers, oscillators, switches, and logic gates. They are also used in integrated circuits, which are the building blocks of most modern electronic devices.
Here is a brief explanation of each option:
- A. Forward-biased: When a small voltage is applied to the base-emitter junction, it causes a large current to flow through the collector-emitter junction. This is because the base-emitter junction is forward-biased, which means that the positive terminal of the voltage source is connected to the base and the negative terminal is connected to the emitter. This forward bias causes the electrons in the base region to be injected into the collector region. The electrons in the collector region then flow out of the collector terminal and into the external circuit.
- B. Reverse-biased: When a small voltage is applied to the base-emitter junction with the positive terminal connected to the emitter and the negative terminal connected to the base, the base-emitter junction is reverse-biased. This reverse bias causes the depletion region to widen, which makes it more difficult for electrons to flow from the base region to the collector region. As a result, very little current flows through the collector-emitter junction.
- C. Nonconducting: When no voltage is applied to the base-emitter junction, the base-emitter junction is nonconducting. This is because there is no potential difference across the junction, and no current flows through it.
- D. Operating in the breakdown region: When a large voltage is applied to the base-emitter junction, the base-emitter junction can enter the breakdown region. In the breakdown region, the junction becomes highly conductive, and a large current can flow through it. However, the breakdown region is not a stable operating region, and the transistor can be damaged if it is operated in this region for too long.
- E. None of the above: None of the above options are correct. The collector diode must be forward-biased for normal operation of the transistor.