MullOverThing

Useful tips for everyday

# Do LEDs follow ohms law?

## Do LEDs follow ohms law?

Neither the incandescent bulb nor the LED will follow Ohm’s Law, neither produces a linear graph.

### Why doesn’t a light bulb follow Ohm’s law?

Resistance of non-ohmic components An example of this is the filament light bulb, in which the temperature rises as the current is increased. Here, Ohm’s law cannot be applied. If the temperature is kept constant for the filament, using small currents, then the bulb is ohmic.

#### Why Ohm’s law is not applicable to diodes and transistors?

Ohm’s law is not applicable for the circuits containing electronic tubes or transistors, diode etc. because such elements are not bilateral i.e. they behave in a different manner when the direction of flow of current is reversed.

What devices obey Ohm’s law?

An example is the p-n junction diode. Current-Voltage Curves: The I–V curves of four devices: two resistors, a diode, and a battery. The two resistors follow Ohm’s law: The plot is a straight line through the origin.

Why is a light bulb not an ohmic material?

A light bulb is non-ohmic because it does not obey Ohm’s law. According to Ohm’s law, “The ratio of potential difference to the current flowing through a conductor is constant, providing all other influences such as temperature are kept constant.” When a material is ohmic, the resistance remains constant when the temperature is kept constant.

## How is the resistance of an led determined?

Measure its resistance with a multimeter and it might be 5 ohms. Connect it to a power supply capable of illuminating it and measure current and voltage and its resistance will have considerably risen (maybe 20 or 30 ohms). Its still a resistor but its resistance changes with power delivered to it.

### Is there anything that doesn’t behave according to Ohms Law?

If you invert your question you see that every thing that behaves according to Ohm’s law must be a resistor. There is only so much that one can do with pure resistance. So logically the anything that doesn’t behave according to ohms law isn’t a resistor. Or any thing that isn’t a resistor won’t behave according to ohms law.

#### Why does water not obey ohm’s law?

Ohm’s law is empirical and was originally derived from obserwing the behaviour of wires of different length. Water doesn’t obey Ohm’s Law, air doesn’t – only conductive materials do, and even then not always.