Skip to main content

The National MagLab is funded by the National Science Foundation and the State of Florida.

Heat Resistance

Metals conduct electricity because their atoms have free electrons that can move between them. As those free electrons move through the metal conductor, some of them crash into things along the way like protons, neutrons, and even other electrons. Those collisions give “resistance” to the movement of the free electrons and generate heat. The resistance is increased further if the metal is exposed to an outside heating source, which causes all particles in the material to move more.

The tutorial below illustrates how the flow of electricity can be impeded by heat.


  1. Observe the simple circuit and identify all its pieces.
  2. Turn on the Bunsen burner.
  3. Watch what happens to the lamp when the flame is heating the wire.
  4. Turn the Bunsen burner off and see how the change affects the lightbulb.

Before the Bunsen burner is turned on, the electricity from the battery flows to the lightbulb and lights it up. The electrons flowing through the wire are experiencing some resistance, but not enough to cause a major impact to the brightness of the bulb. When the flame is on, however, the heat excites the atoms in the wire which causes them to vibrate significantly. The extra bouncing around inside the wire creates more collisions, and therefore more resistance. The lightbulb dims when the flow of electrons is reduced.

You probably aren’t torching your electrical wires, so this tutorial setup might seem a little impractical. But it illustrates a simple physics phenomenon that challenges engineers anytime they need to conduct electricity in an extremely hot environment.