Question

Does a LED lamp obey Ohms law?

Answer 1

A typical LED (Light Emitting Diode) does not strictly obey Ohm's Law in the same way a simple resistor does, but it is still influenced by the principles behind Ohm's Law.

Ohm's Law states that the current through a resistor is directly proportional to the voltage across it and inversely proportional to the resistance, given by the formula:  
\[ I = \frac{V}{R} \]

However, LEDs are semiconductor devices, and their behavior is more complex. Here's why:

1. Non-Linear Relationship: Unlike resistors, the relationship between voltage and current in an LED is non-linear. As you increase the voltage across an LED, the current doesn't increase in a straight line. Instead, it increases rapidly once a certain threshold voltage (called the "forward voltage") is reached. Before that, the LED conducts very little current.
   

1. Forward Voltage: LEDs have a characteristic forward voltage (typically between 1.8V and 3.3V, depending on the type of LED), which must be overcome before they begin to emit light. Once the voltage surpasses this threshold, the current increases, but not in a linear fashion as Ohm's Law would predict for a resistor.
   

1. Constant Current: In practice, LEDs are often powered using a constant current driver, which regulates the current to a specific value. This ensures that the LED receives the correct current to emit light without burning out. In this case, the LED's behavior is more controlled by the driver circuit than by simple voltage-to-current relations.
   

In summary, while LEDs don't directly obey Ohm's Law in the strict sense, their behavior can be understood using similar principles if we account for their non-linear characteristics.