# Turn on the LED light

Placed on

First a word of explanation.

LED stands forlight emitting diode. this means that it is a diode and it is not a real loader in your circuit. You probably know that if a circuit has no load, it will short circuit. To prevent this, we must place a series resistor in your circuit. In this article I also explain how to calculate what value this resistor will have.

example of an LED lamp.
To determine a series resistance, we need an LED characteristic, as shown above.

We are now going to calculate the series resistance. Let's say we use a red LED and a 9 volt power supply. If we take a look at the LED characteristic, we can choose to let 10mA flow through the LED. this means that there will be about 1.6 volts across the led. If we then do 9 - 1.6 we end up with 7.4 volts across the resistor. Then we can now calculate with ohm's law (R=U/I) how many ohms the resistor will have.

R = 7.4 / 0.01 = 740 ohms.

Because there is no 740 ohm resistor in the E12 series, we take a slightly higher resistor of 820 ohm.

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Now you can connect everything to the breadboard and the LED will light up nicely at 10mA without shorting the circuit.

The end result