Answer / techyjohn

1- to rectify an AC voltage into a DC one, such as for an alternator output

2- (zener diode) to provide a reference voltage, such as for regulating the field current for an alternator.

3- (variactor diode) to provide an adjustable capacitance which can be adjusted by a DC voltage, such as for tuning radio stations

Diode equation:

The diode equation gives an expression for the current through a diode as a function of voltage. The Ideal Diode Law, expressed as:

I=I0((e^qv/kt)-1)

where:
I = the net current flowing through the diode;
I0 = "dark saturation current", the diode leakage current density in the absence of light;
V = applied voltage across the terminals of the diode;
q = absolute value of electron charge;
k = Boltzmann's constant; and
T = absolute temperature (K).

The "dark saturation current" (I0) is an extremely important parameter which differentiates one diode from another. I0 is a measure of the recombination in a device. A diode with a larger recombination will have a larger I0.

Note that:

I0 increases as T increases; and
I0 decreases as material quality increases.
At 300K, kT/q = 25.85 mV, the "thermal voltage"

Answer / yogesh kumar

diode is use in any case.
1.power controlar
2.power measurement

i want exam information bhel, nal, hal, bel you have any idea or any question papers or placement papers please send soon

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