Ohm's Law is a fundamental principle in electrical circuits that relates the voltage, current, and resistance of a component. It states that the current through a component is directly proportional to the voltage across it and inversely proportional to its resistance. Mathematically, Ohm's Law is represented as:
V = I * R
where:
V = Voltage across the component (in volts)
I = Current through the component (in amperes)
R = Resistance of the component (in ohms)
However, Ohm's Law is not directly applicable to diodes in reverse breakdown because diodes don't behave like linear resistors. In reverse bias, when the voltage is applied in the opposite direction of the diode's forward conduction, a diode typically has a very high resistance and does not allow any significant current to flow. This is the case for a normal diode in reverse bias.
However, in the context of reverse breakdown, the situation is different. Reverse breakdown occurs when a voltage applied in the reverse direction is so high that it causes the diode to break down and conduct heavily in the reverse direction. During reverse breakdown, the diode effectively loses its high resistance and starts conducting significant current.
When this breakdown occurs, Ohm's Law can be loosely applied to explain the voltage drop across the diode. The voltage drop across the diode in reverse breakdown can be approximately modeled using Ohm's Law by considering the diode's equivalent resistance in reverse breakdown, which is often referred to as the dynamic or incremental resistance (r).
The approximate relationship for the voltage drop (V_diode) across the diode during reverse breakdown, using Ohm's Law, can be expressed as:
V_diode ≈ I_reverse * r
where:
V_diode = Voltage drop across the diode during reverse breakdown (in volts)
I_reverse = Current flowing through the diode during reverse breakdown (in amperes)
r = Dynamic or incremental resistance of the diode during reverse breakdown (in ohms)
It's important to note that the reverse breakdown behavior of diodes is not linear, so the resistance (r) can vary depending on the diode's construction and the magnitude of the reverse current. Additionally, the actual breakdown behavior might have more complex characteristics, especially in specialized diodes designed for specific applications.
In summary, while Ohm's Law is not directly applicable to the entire reverse breakdown behavior of diodes, it can be used as a basic approximation to understand the voltage drop across the diode during reverse breakdown when it starts to conduct significant current.