How is Ohm's Law used in determining the current through a diode in forward bias?
1 Answer
Ohm's Law is not directly applicable to determining the current through a diode in forward bias. Ohm's Law, which states that the current (I) flowing through a conductor between two points is directly proportional to the voltage (V) across the two points and inversely proportional to the resistance (R) of the conductor (I = V/R), is primarily applicable to ohmic resistors, where the resistance remains constant regardless of the applied voltage.
Diodes, on the other hand, are nonlinear devices, and their behavior is described by more complex equations. In forward bias, when the diode is conducting current, its behavior can be approximately described by the Shockley diode equation:
I = Iā * (e^(V / (n * V_T)) - 1)
Where:
I is the diode current in forward bias.
Iā is the reverse saturation current (or scale current) of the diode.
e is the base of the natural logarithm, approximately equal to 2.71828.
V is the voltage across the diode.
n is the ideality factor, which accounts for deviations from ideality (typically around 1 for silicon diodes).
V_T is the thermal voltage, given by k * T / q, where k is Boltzmann's constant, T is the temperature in Kelvin, and q is the charge of an electron.
As you can see, this equation is nonlinear due to the presence of the exponential term, and it does not directly follow Ohm's Law. Therefore, Ohm's Law cannot be used to determine the current through a diode in forward bias. Instead, the Shockley diode equation or other more specific diode models are used to analyze diode behavior in forward bias.
Diodes, on the other hand, are nonlinear devices, and their behavior is described by more complex equations. In forward bias, when the diode is conducting current, its behavior can be approximately described by the Shockley diode equation:
I = Iā * (e^(V / (n * V_T)) - 1)
Where:
I is the diode current in forward bias.
Iā is the reverse saturation current (or scale current) of the diode.
e is the base of the natural logarithm, approximately equal to 2.71828.
V is the voltage across the diode.
n is the ideality factor, which accounts for deviations from ideality (typically around 1 for silicon diodes).
V_T is the thermal voltage, given by k * T / q, where k is Boltzmann's constant, T is the temperature in Kelvin, and q is the charge of an electron.
As you can see, this equation is nonlinear due to the presence of the exponential term, and it does not directly follow Ohm's Law. Therefore, Ohm's Law cannot be used to determine the current through a diode in forward bias. Instead, the Shockley diode equation or other more specific diode models are used to analyze diode behavior in forward bias.