Rate of conductive heat transfer

Definition

Rate of conductive heat transfer is the amount of heat energy transferred per unit time through a material due to temperature difference. It is primarily described by Fourier's law of heat conduction.

5 Must Know Facts For Your Next Test

1. Fourier's law states that the rate of heat transfer through a material is proportional to the negative gradient in temperature and the area through which the heat flows.
2. The formula for conductive heat transfer rate is $Q = -kA \frac{dT}{dx}$, where $Q$ is the heat transfer per unit time, $k$ is the thermal conductivity, $A$ is the cross-sectional area, and $\frac{dT}{dx}$ is the temperature gradient.
3. Thermal conductivity ($k$) varies with materials; metals typically have high thermal conductivities, while insulators have low thermal conductivities.
4. Units for the rate of conductive heat transfer are typically Joules per second (Watts).
5. Factors that affect the rate include material type, cross-sectional area, thickness of the material, and temperature difference.

Review Questions

• What does Fourier's law state about conductive heat transfer?
• How does thermal conductivity affect the rate of conductive heat transfer?
• Which factors can influence the rate at which heat conducts through a material?

Related terms

Thermal Conductivity: A measure of a material's ability to conduct heat. High values indicate good conductors like metals.

Temperature Gradient: The rate at which temperature changes with distance within a material. Represented as $\frac{dT}{dx}$ in Fourier's law.

Fourier's Law: $Q = -kA \frac{dT}{dx}$; describes how heat conduction occurs in terms of thermal conductivity, temperature gradient, and cross-sectional area.