Explainer: Temperature and electrical resistance

Temperature measures the motion of molecules


Temperature and electrical resistance are all about the movement of molecules.

Karen Blakeman/Flickr/ (CC BY-NC 2.0)

Temperature measures the average motion of atoms and molecules in a material. A higher temperature indicates that atoms and molecules have more energy. They also are moving or vibrating faster. To understand how temperature affects electrical resistance, consider the two types of charged particles inside an atom: negatively charged electrons, whose motion generates current; and positively charged protons, which are 1,800 times heavier. Because electrons are much lighter, they don’t require as much energy to move. It takes a lot more energy, or heat, to get protons moving.

Imagine a hallway where half of the population — all of them electrons — travels in the same direction. Meanwhile, the other half — protons — doesn’t have enough energy to move at all. This would represent a cold wire. As the wire heats up, the protons start vibrating. As their motion becomes more random, these protons are more likely to get in the way of the electrons. That disrupts the current flow. As a result, the higher the temperature, the higher the resistance to the flow of electrons — and electricity.

Power Words

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atom   The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and neutrally charged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.

current   A fluid body — such as of water or air — that moves in a recognizable direction. (in electricity) The flow of electricity or the amount of electricity moving through some point over a particular period of time.

electric current  A flow of charge, called electricity, usually from the movement of negatively charged particles, called electrons.

electricity   A flow of charge, usually from the movement of negatively charged particles, called electrons.

electron  A negatively charged particle, usually found orbiting the outer regions of an atom; also, the carrier of electricity within solids.

particle  A minute amount of something.

proton  A subatomic particle that is one of the basic building blocks of the atoms that make up matter. Protons belong to the family of particles known as hadrons.

wave  A disturbance or variation that travels through space and matter in a regular, oscillating fashion.


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