Light Dependent Resistors (LDRs) - Definition, Construction, Workings and Applications: Light dependent resistors (LDRs) are made from cadmium sulphide containing no or very few free electrons when not illuminated. Its resistance is then quite high.…
Photodetectors - Definition and Applications: Photodetectors are the semiconductor devices that can detect optical signals through electronic processes. The extension of coherent and incoherent light sources into the far-infrared region on one hand and the…
Photoconductivity - Definition, Working and its Applications: Photoconductivity - When excess electrons and holes are produced in a semiconductor, there is a corresponding increase in conductivity of a sample as indicated by the following equation…
Luminescence - Definition and Types: When a system absorbs energy in some form or other, it may be partly re-emitted as radiation. This phenomenon is called luminescence. Luminescence may occur in solids (crystals or glasses)…
Photon Absorption Coefficient: Photon Absorption Coefficient - When light falls on a semiconductor, the photons may be absorbed or they may propagate through the semiconductor depending on the photon energy (E) and the band gap…
Optical Absorption in Electronics: As discussed in Art. 25.3, light waves can be treated as particles, which are referred to as photons. The energy of a photon is E = hf where h is Plank's…
What is Wave Particle Duality? Since waves exhibit particle-like behavior, then the particles also should exhibit wave—like properties. This theory (de Broglie) is based on the existence of a wave particle duality principle. The momentum…
What is Photoelectric Effect?: When monochromatic light is incident on a clean surface of a material, then under certain conditions, electrons, also called photoelectrons, are emitted from the surface. The electrons in the metal absorb…
What is Optoelectronic Devices? Optoelectronics is the technology that combines optics and electronics and the devices based on this technology are known as optoelectronic devices. These devices include emitters, sensors and optocouplers or optoisolators. These…
Shifted Unit Step Function: This Shifted Unit Step Function is defined by the equation for a step function which changes abruptly at the time t = + a. In general, the step function has unit…
