Forward bias characteristics:

• The diode conducts when the p-side is connected to the positive terminal and the n-side to the negative terminal.
• A noticeable current flow begins once the forward bias voltage reaches approximately 0.5V to 0.7V (depending on the material, silicon, or germanium).
• After this threshold, a small increase in voltage results in a large increase in current.

Reverse bias characteristics:

• When the p-side is connected to the negative terminal and the n-side to the positive terminal, the diode does not conduct (except for a small leakage current).
• For Zener diodes, conduction occurs in reverse bias after the breakdown voltage is reached.

Breakdown characteristics:

• In reverse bias, if the reverse voltage exceeds a specific value (breakdown voltage), the diode may allow a large current to flow, potentially damaging the diode (unless it is a Zener diode designed for this purpose).

Dynamic Resistance (Rd):

• This represents the diode's resistance to AC voltage. It's calculated as the change in AC voltage divided by the change in AC current. It varies depending on the operating point on the diode's I-V curve.

Static Resistance (Rs):

• This is the resistance to DC voltage. It's calculated as the DC voltage across the diode divided by the DC current through it. Similar to dynamic resistance, it also depends on the operating point on the diode's I-V curve.