220Ω Resistor
The standard current-limiting resistor for a 5V-powered red or yellow LED — one of the two values (with 330Ω) every beginner kit includes.
How this component works
A resistor opposes the flow of electric current. The relationship between voltage, current, and resistance follows Ohm's Law: V = I × R. The higher the resistance in ohms (Ω), the less current flows for a given voltage.
Resistors are used to limit current to protect other components (like an LED), to divide voltage between two points, or to set bias points in transistor circuits. Real resistors are also rated for power dissipation (commonly 1/8W, 1/4W, 1/2W, 1W) — exceeding this rating causes the resistor to overheat and fail.
Fixed resistors have a color-coded value that doesn't change. A potentiometer is the variable version of a resistor, and both use the same underlying physics in CircuitForge's solver.
Common Use Cases
- Current-limiting resistor in series with a red/yellow/green LED on a 5V supply
- Pull-down or pull-up resistor where a lower value is needed for faster switching
- Base resistor for driving a small-signal NPN transistor from a 5V logic pin
Frequently Asked Questions
Will a 220Ω resistor work for any LED?
It works safely for most low-power red, yellow, and green LEDs on 5V, but blue and white LEDs have a higher forward voltage and draw less current through the same resistor — 330Ω is more common for those on higher-voltage supplies. Check the LED's forward voltage first.
What happens with a lower resistance, like 100Ω?
Less resistance means more current reaches the LED. If it pushes the LED past its rated forward current, the LED will run hotter and its lifespan drops — in the simulator you can raise the source voltage and watch the current climb to see this directly.