Practice MCQ Questions and answers on Physics-GK

In electronics, a diode is an electronic device that allows current to flow in one direction only. It is mainly used as a rectifier diode that lets electrical current flow in only one direction and is mainly used for power supply operation. Rectifier diodes are used for changing alternating current into direct current.

The total width of the depletion region is a function of applied reverse-bias and impurity concentration. Forward bias decreases the depletion region width whilst reverse bias increases it.

The impurity atoms with which pure silicon should be doped to make a p-type semiconductors are those of Boron and Aluminium that are trivalent in nature. So, they should be added in pure silicon to make p-type semiconductors.

The Zener diode is like a general-purpose signal diode. When based in the forward direction it behaves just like a normal signal diode, but when a reverse voltage is applied to it, the voltage remains constant for a wide range of currents and hence widely used for regulated electric supply. The device was named after Clarence Zener, who discovered this electrical property. Many diodes described as “Zener” diodes rely instead on avalanche breakdown as the mechanism. Common applications include providing a reference voltage for voltage regulators, or to protect other semiconductor devices from momentary voltage pulses. Zener diodes are widely used as voltage references and as shunt regulators to regulate the voltage across small circuits.

A NOT gate can be implemented by a single transistor.

A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power.The transistor invented in 1948 was well suited to the hearing aid application due to low power and small size; hearing aids were an early adopter of transistors. Transistors replaced the need for batteries in hearing aids.

Semiconductors are insulators at low temperatures and reasonably good conductors at higher temperatures. As temperature increases, the semiconductor material becomes a better and better conductor.

Some components like transformers and inductors cannot be integrated into an IC except for very specialized high frequency applications. They have to be connected externally to the semiconductor pins. In general, transformers are located in circuit boards as separate components and cannot be integrated into semiconductor based integrated circuits.

A metal semiconductor junction diode is called Schottky diode.

A universal gate is a gate which can implement any Boolean function without need to use any other gate type. The NAND and NOR gates are universal gates.