LED Brightness Control with Resistor

In this experiment you will observe how a resistor affects the brightness of an LED. Resistors are used in circuits to control the amount of current flowing through components.

By changing the resistor value in a simple LED circuit, you can directly observe how current influences LED brightness.


Goal

Understand how resistors control current in a circuit and how changing resistance affects LED brightness.

What You Need

Circuit

Connect the resistor in series with the LED and battery.

Battery positive → resistor → LED → battery negative.

The resistor limits the amount of current that flows through the LED.

Circuit Diagram

LED Brightness Control with Resistor

Circuit Diagram showing a LED Brightness Control with Resistor.

Breadboard Layout

The following layout shows how the circuit can be built on a breadboard.

Breadboard layout of the LED Brightness Control with Resistor experiment

Practical breadboard wiring for the LED Brightness Control with Resistor experiment. Also swap the battery terminal if LED not turn on.

Steps

What You Should Observe

When a lower value resistor is used, more current flows through the LED and the LED appears brighter.

When a higher value resistor is used, the current decreases and the LED becomes dimmer.

Why This Happens

Resistors limit the flow of electric current in a circuit. According to Ohm's Law, the current flowing through a circuit decreases when resistance increases.

Since LED brightness depends on the current passing through it, increasing resistance reduces brightness while decreasing resistance increases brightness.

Try This

Always use a resistor when connecting LEDs to a power source. Without a resistor, too much current may damage the LED.