A solar cell, also known as photovoltaic cell, convert light energy directly into electricity (or) electric potential difference by photovoltaic effect

A P-N junction diode which converts an optical signal into electric current is known as photo diode.

(i) Seven-segments displays
(ii) Indicator lamps on the front panel of the scientific and laboratory equipments.
(iii) Traffic signals, exit signs, emergency vehicle lighting etc

(i) Voltage regulators
(ii) Peak clippers
(iii) Calibrating voltages

Electric field is strong enough to break (or) rep tune the covalent bonds in the lattice and there by generating electron - hole pairs. This effect is called Zener effect.

The ratio of the output de power to the ac input power supplied to the circuit.

The process in which alternating voltage or alternating current is converted direct voltage or direct current is called rectification.

A graph is plotted by taking the forward bias voltage (V) along the x- axis and the current (I) through the diode along y-axis. This graph is called the forward V-I characteristics.

If the positive terminal battery is conneted to the n-side and the negative potential to the p-side, the junction is said to be reverse biased.

If the positive terminal of the external voltage source is connected to the p-side and the negative terminal to the n-side, it is called forward bias.

The external voltage applied to the p-n junction is called bias voltage.

The internal repulsion of the depletion layer stops further diffusion of free electrons across the junction. This difference in potential across the depletion layer is called barrier potential.

The energy gap between the valance band and conduction band is called forbidden energy gap

The energy band formed due to the valence orbitals is called valance band and that formed due to unoccupied orbital is called conduction band.

Band of very large number of closely spaced energy levels in a very small energy range is known as energy band.