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Resistor

physical science Maturity 11-13 Next article →

A resistor is a tiny but vital part of an electronic circuit.

Carbon and ceramic resistors of different power ratings
Carbon and ceramic resistors of different power ratings

Its main job is to provide electrical resistance. This means it limits how much electricity can flow through a path. Engineers use them to reduce current or adjust signal levels. They can also divide voltages or protect other parts of a device. Resistors are found in almost all electronic equipment today.

3 Resistors
3 Resistors

You can picture how a resistor works by thinking about water. Imagine water flowing through a pipe in a house.

ResistanceHydraulicAnalogy2
ResistanceHydraulicAnalogy2

If that pipe gets clogged with hair, the water flows much slower. It takes more pressure to push the water through the clog. Electricity works in a similar way. Pushing current through a large resistance is like pushing water through a clogged pipe. It requires a larger push, called voltage, to keep the current moving.

Resistor symbol America
Resistor symbol America

Scientists use a rule called Ohm's law to understand this relationship. This law says that the voltage across a resistor is proportional to the current passing through it. The constant number that connects them is the resistance.

Resistor symbol Europe
Resistor symbol Europe

We measure this resistance in units called ohms, shown by the symbol Ω. This unit is named after Georg Simon Ohm. For very small or very large values, we use prefixes. We might use milliohms for tiny amounts or megohms for huge ones.

ResistorColorCodeGuide
ResistorColorCodeGuide

There are different ways to connect resistors together in a network. If you connect them in a series, they sit end to end. The total resistance is just the sum of all their individual values.

resistors in series
resistors in series

If you connect them in parallel, they sit side by side. This works differently because the total resistance is calculated using reciprocals.

resistors in parallel
resistors in parallel

Some networks are very complex and mix both types of connections. Engineers use special math to solve these tricky circuit puzzles.

When electricity flows through a resistor, it turns into heat.

This is called power dissipation. If a resistor handles too much power, it can get very hot. This heat might damage the part or even cause a fire.

Danotherm HS50 power resistor
Danotherm HS50 power resistor

Some resistors are built to be flameproof to stay safe. Older styles, like carbon composition resistors, were common in the 1960s.

Old Radio Resistors
Old Radio Resistors

Today, we use many different types of resistors for all kinds of jobs.

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🖼️ Images & Media (23)
File:Resistor symbol America.svg
Resistor symbol America.svg
File:Resistor symbol Europe.svg
Resistor symbol Europe.svg
File:Carbon and ceramic resistors of different power ratings.jpg
Carbon and ceramic resistors of different...
File:ResistanceHydraulicAnalogy2.svg
ResistanceHydraulicAnalogy2.svg
File:resistors in series.svg
resistors in series.svg
File:resistors in parallel.svg
resistors in parallel.svg
Resistor warming thermal video.webm
File:Danotherm HS50 power resistor.jpg
Danotherm HS50 power resistor.jpg
File:USSR power resistor VZR 12W.JPG
USSR power resistor VZR 12W.JPG
File:Sil resistor.png
Sil resistor.png
File:3 Resistors.jpg
3 Resistors.jpg
File:Résistances anciennes annees 50.jpg
Résistances anciennes annees 50.jpg

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