# Series resistors

Connecting resistors in series does a few things.

• Increases resistance
• Divides voltage

## Increased resistance

Series resistors just add up each of their resistance, which becomes the total resistance. In the diagram below, we have three 1,000Ω resistors in series. So together they have a total of 3,000 ohms of resistance.

### Voltage divider

Series components always split up/divide/drop voltage from the power supply unless they have 0Ω of resistance.

The series resistors divide up whatever voltage is given to them based on their percentage of the series circuit resistance.

Equal value resistors are easy to calculate. Two equal value series resistors will have half the supply voltage across each of them.

Three equal value resistors connected in series as a voltage divider will have 1/3 of the supply voltage across each of them.

#### Power sharing – Heat generation/dissipation

The diagram in the last section above shows how two series 100Ω resistors with 5 volts across them (2.5V each) will both pass the same amount of current (0.025A or 25mA) as a 200Ω resistor with 5V across it . The wattage of each component is the voltage across it times the current through it.

Using a single 200Ω resistor with 5V across it will also pass 0.025A, and 0.025A x 5V = 0.125W. It will be twice as hot as either of the two series 100Ω resistors which will split the power dissipation. 2.5V x 0.025A = 0.0625W for each of the two series 100 ohm resistors.

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##### Related topics:

Other basic electronics topics that you should know before moving on to more advanced topics.

555 timer is an integrated circuit (IC). Being an IC, it has complex circuitry combined in a single package with external pins/terminals to connect to other circuitry. You can easily make all kinds of fun circuits with just a 555 timer and the components covered above, so I think it’s a good component to learn next.

Transistors will probably be the most challenging components to learn. Understanding them will help you understand all of electronics much better, and help you the most in being creative while designing your own circuits.

Other topics:

These pages are still being compiled.

Circuits covered more quickly series: