Why is the forward bias resistance of a diode very low compared to reverse bias?

Hello everyone,
I wanted to know like why the resistance of a diode in forward bias condition is very low

Hi Vijay,

You could check this pdf for reference.

1. PN diodes (forward bias), small signal model, BJTs
2. Diode Resistance

Hope it helps,

Hi,

What do you mean by low resistance in forward bias condition? The resistance of a diode in a FB condition depends on the voltage you supply it with. If the diode is silicon, it needs 0.7V to conduct while 0.3 V if germanium.

Let me quote what yahooanswers have to say:
" The resistance of a pn junction varies over a wide range of resistance values even when biased in the forward direction..

Junction resistance in forward bias direction approaches infinity for all forward bias Voltages greater than 0 Volts but less than enough to cause the diode to start conduction. Silicone diodes start conducting at about .7 Volts forward bias (Vpn). At maximum rated current conduction Vpn increases but very little.

Instantaneous junction resistance in the forward direction is equal to Vpn/i for all values of bias Voltage (Vpn). During the time that i = 0, the forward junction resistance is approaching infinity."

Hope this helps.
Kevin

See this article.
http://www.learningaboutelectronics.com/Articles/Diode-resistance.php
A diode is not like an ordinary resistor, it is a semiconductor material, and the laws governing its behavior are dictated by semiconductor physics. So you need to look at the physics to understand why the diode behaves as it does.
http://hyperphysics.phy-astr.gsu.edu/hbase/solids/diod.html
Its resistance is therefore not related in any way to ohms law that you will encounter with a restive device.
Cheers,
Richard