Why does resistors heat up

I know that there would be less current with higher resistance but since there is more resistance the lack of current would be made up for with more heat generated.

Thus, the power dissipated by just the wire is greater than the power dissipated by the wire plus resistor. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Why do resistors heat up less than short circuited wires if resistors have higher resistance and therefore turn more voltage into heat?

Ask Question. Asked 3 years, 7 months ago. Active 3 years, 7 months ago. Viewed times. Under excessive voltage, a resistor generates so much heat that it cannot dissipate the heat quickly enough to prevent burning. Resistors are designed to operate under specific voltages. The voltage rating of a resistor is designated by its wattage power value. When a resistor is functioning under a normal voltage load, it is operating as it should under a voltage that meets or falls below its power rating.

The resistor will feel cool to warm by touch. The relatively low temperature is a result of the resistor acting as a semiconductor, meaning that it is allowing only a specific amount of current to flow through. Current is the flow of electrons. When electrons meet resistance, as they do in a semiconductive material, they produce heat.

Resistors are designed to dissipate the heat so the semiconductive material is not damaged. When a resistor is placed under a voltage that approaches the upper limits of its power rating, the resistor generates more heat than normal.

This is due to the voltage attempting to force more current electrons through the resistor than it is designed to pass. The resistor will be hot to touch and a faint whiff of burning may be detectable.

These changes in resistance cannot therefore be explained by a change in dimensions due to thermal expansion or contraction.

In fact for a given size of conductor the change in resistance is due mainly to a change in the resistivity of the material, and is caused by the changing activity of the atoms that make up the material.

The reasons for these changes in resistivity can be explained by considering the flow of current through the material. The flow of current is actually the movement of electrons from one atom to another under the influence of an electric field.

Electrons are very small negatively charged particles and will be repelled by a negative electric charge and attracted by a positive electric charge. Therefore if an electric potential is applied across a conductor positive at one end, negative at the other electrons will "migrate" from atom to atom towards the positive terminal. Only some electrons are free to migrate however. Others within each atom are held so tightly to their particular atom that even an electric field will not dislodge them.

The current flowing in the material is therefore due to the movement of "free electrons" and the number of free electrons within any material compared with those tightly bound to their atoms is what governs whether a material is a good conductor many free electrons or a good insulator hardly any free electrons. The effect of heat on the atomic structure of a material is to make the atoms vibrate, and the higher the temperature the more violently the atoms vibrate.

In a conductor, which already has a large number of free electrons flowing through it, the vibration of the atoms causes many collisions between the free electrons and the captive electrons.