Technical Definition

Resistance is a term used in electrical circuits to describe the impedance or friction in a circuit. Resistance is a ward that has man applications and meaning, ranging from a child that does not want to take a bath, to the French civilians during World War II.  The word resistance has its roots in the Latin word resistere. Re- meaning “against” and –sistere meaning “to stand firm, take a stand”.

Some common uses of resistance are” the French opposition to Nazi occupation during World War II, the capacity or ability of a disease to  fight anti-biotics, or the natural ability of an organism to fight against a disease or illness.  Resistance also means an opposing or retarding force.

Specific to electricity and electrical engineering, resistance is a measure of the ration of the change in voltage, divided by current flowing through the circuit. Electrical Resistance is measured in ohms, named for the German Physicist that lived from 1787- 1854 George Simon Ohm.

George Simon Ohm

One of the best ways to picture resistance is someone trying to walk down a sidewalk.  If there are alot of people on the side walk, or alot of resistance in a circuit, then you cannot walk as fast as you would like.  But if there is no one on the sidewalk, or very little resistance in the circuit, when you aren’t stuck shuffling shoulder to shoulder with a plethera of people you don’t know, you can run as fast as you want.  If there is little resistance in a circuit then power flows freely.

Carbon Film Resistors

Resistors work by changing electrical current into heat, and then allowing that heat to dissapate into the air.  Just like when you rub your hands together, the friction between your hands changes kinetic energy of your hands into heat energy that can be felt, resistors change electrical engergy into heat.