Duduli

The conditions which must be satisfied by a function f(x) to be expanded using Fourier series are called Dirichlet conditions.

Dc value of Ac is that value of steady current which sends same amount of charge through a circuit in same time as is done by Ac in one of cycle.

It is the forward voltage at which the current through the junction starts to increase rapidly.

An expression of more than two algebraic terms, especially the sum of several terms that contain different powers of the same variable.  e.g  Legendre & Hermite polynomial

It is the minimum reverse voltage at which pn junction breaks down with sudden rise in reverse current.

When external d.c voltage applied to the junction is in such a direction that it cancels the potential barrier, thus permitting current flow, it is called forward biasing.

A junction diode which acts as a variable capacitor under changing reverse bias is known as a varactor diode.

A transistor consists of two pn- junction formed by sandwiching either p- type or n- type Semiconductor between a pair of opposite types. Accordingly there are two types of transistors namely  (i) n-p-n transistor (ii) p-n-p transistor

A tunnel diode is a pn junction that exhibits negative resistance between two values of forward voltage(i.e between peak point voltage and valley point voltage). A conventional diode exhibits positive resistance when it is forward biased or reverse biased. However, if a Semiconductor junction diode is heavily doped with impurities, it exhibits negative resistance (i.e current decreases as the voltage is increased) in certain regions in the forward direction. Such a diode is called tunnel diode.

A photo diode is a reversed-biased silicon or germanium pn junction in which reverse current increases when the junction is exposed to light. The reverse current in a photo-diode is directly proportional to the intensity of light falling on it's on junction.This means that greater the intensity of light falling on the pn junction of diode the greater will be the reverse current.

A function f(x) is said to be periodic if their exist a number (T>0) such that f(x+T)=f(x). Again, f(x+nT)=f(x)

A thermos flask consists of a double walled glass bottle. The space in between the two bottles is evacuated and sealed. Walls are highly polished (i.e silvered) to avoid radiation of heat.The outer polished surface of A does not radiate heat. Even if a little quantity of heat is radiated by A, most of it is reflected back by the polished surface of B. The evacuation of the space in between A & B helps in the elimination of the loss of heat by conduction and convection. Similarly ice kept inside the flask will not melt for a long time because heat radiations from outside cannot enter the inside of the bottle.

Fourier series is an infinite series representation of periodic function in terms of trigonometric function sine & cosine.