The resistor is very useful component in electronic circuits. You will see resistors everywhere in electronic circuits. Why we use resistors in every electronic circuit? We use the resistor to control the voltages and the currents in our circuits.
Let’s say that, you have a 12V battery and you want to turn on an 5v LED. If you connect the battery directly to the LED, 12v of the battery will fl ow through the LED! but LED required voltages are 5v so, after some time the LED will become very hot or burn out.
But, if you put a resistor in series with the LED, you can get required voltages for Your LED
Resistor Symbole Used in Diagrams
A common way to use resistor is to control the current for the LED
A standard LED can handle only up to 20 to 30 mA around. If the current it much bigger than that,
the LED will be die quickly.
Let’s say that, the LED in circuit above needs 15 mA to give a better light, and it has a
voltages drop of 2 volts. (These values should be specified by the supplier when
If anyone have a 9 Volt battery that, you would like to power it with which resistor value
do you need?
The voltage specified for LED is the voltage drop the LED will have under normal condition.