ohm – the unit of electrical resistance

(pronounced ohm)

To remember the meaning of ohm, use the following mnemonic:

Inside my home (ohm) I was resistant to electricity (electrical resistance).

An ohm is the unit used to measure electrical resistance, which is represented by the symbol Ω (the Greek letter omega). Resistance is a measure of how difficult it is for electrical current to flow through a component or material. One ohm is defined as the resistance that allows one ampere of current to flow when one volt is applied across it. Components with high resistance, such as long, thin wires, make it harder for current to flow and therefore have a high value measured in ohms, while good conductors like thick copper have very low resistance. 

A resistor is a component designed to create resistance and limit the flow of current in a circuit. Different resistors provide different levels of resistance in the form of ohms, indicated by different colours on the body of a resistor. 

Electrical circuits have resistors built in primarily to control and limit the flow of electric current preventing sensitive components from being damaged by excess electricity.

To remember the formula for resistance recall the physics electrical formula mnemonic:

Here you can clearly see that 

`\text(resistance)  =  \text(volts)/\text(amps)`

For example, if a 6 volt battery drives 2 amps through a resistor in a circuit the resistance is 3 ohms.

`\text(resistance)  =  (6\text(v))/(2\text(a)) =  3  \text(ohms)`