# Electronics - Diodes and Applications - Discussion

Discussion Forum : Diodes and Applications - General Questions (Q.No. 1)
1.
What is a varistor?
a voltage-dependent resistor
a voltage-dependent diode
a current-dependent resistor
a current-dependent diode
Explanation:
No answer description is available. Let's discuss.
Discussion:
22 comments Page 1 of 3.

A varistor is an electronic component with a "diode-like" nonlinear current-voltage characteristic. The name is a portmanteau of variable resistor. Varistors are often used to protect circuits against excessive transient voltages by incorporating them into the circuit in such a way that, when triggered, they will shunt the current created by the high voltage away from sensitive components. A varistor is also known as Voltage Dependent Resistor or VDR. A varistor's function is to conduct significantly increased current when voltage is excessive.

Bharath kumar.S.P said:   9 years ago
The forward and reverse biased states of a diode can be compared to a variable resistor. A forward biased diode will drop only .3 or .7 V.

That corresponds to an internal resistance in the anode that drops from several Kilo-ohms at the point where conduction begins to several ohms where a diode is conducting heavily.

In the reverse bias state, resistance will be in the Mega-ohms until breakdown voltage is reached.

DEEPAK JHA said:   1 decade ago
When voltage drop increases across the resistor, power dissipation also increase because of P=VI and thus temperature increases.

Due to increase in temperature there are a lot of free electrons generates in the wire which moves randomly in all direction and provide barrier in the path of current & hence the resistance of wire increase.

I have a small doubt. High barrier potential is provided when the temperature is increased in reverse bias. Then it offers high resistance. When the temperature is increased in forward bias, in that situation there is small barrier potential. Then current is high and resistance is small.

Jayasankar said:   8 years ago
Varistor is an electronic component with an electrical resistance that varies with the applied voltage. It is also known as a Voltage Dependent Resistor (VDR).

Varistor is a special type resistor it depend upon the voltage varistor also called as voltage depending resistor.

This is a resistor whose value changes with the applied voltage. We can get this type of resistors from FETs.

Siddharth said:   2 years ago
Varistor is a semiconductor diode whose value of resistance depends on voltage applied, its not a resistor.
(1)

Kishan TJ said:   1 decade ago
Varistor is the special type of resistor, its changes the resistance un accordance with the temperature.

Donald said:   10 years ago
If referred as a semiconductor diode or a voltage dependent resistor, does it sound correct? I doubt.