This is the first circuit we build on a breadboard. I will provide the calculations to determine the appropriate resistor value. We will use **Ohm's Law** and the following formula:
R = Vs-VL/I
Where:
(R) is the resistor value in ohms
(Vs) is the supply voltage (e.g., 9V in this case).
(VL) is the forward voltage drop of the LED (typically 2V to 3V, depending on the LED type).
(I) is the desired current through the LED (usually 10-30mA for most LEDs).
### Example Calculation:
Given:
(Vs) = 9V
(VL) = 2V(assuming a red LED)
(Desired current) I = 20mA = 0.02A
Now, calculate the resistor value:
R = 9V -2V/0.02A = 7V/0.02A = 350
So, a resistor of **350Ω** would limit the current to 20mA. In practical terms, a **330Ω resistor** is often used since it is a standard value and provides a close enough current limit for safe LED operation.
