Conduction, Convection and Radiation
Heat travels by conduction (dQ/dt = kA dT/dx), by convection through bulk fluid motion, and by radiation (Stefan's law, P = e σ A T4).
What is Conduction, Convection and Radiation?
Heat travels by conduction (dQ/dt = kA dT/dx), by convection through bulk fluid motion, and by radiation (Stefan's law, P = e σ A T4).
Key formula / rule: Conduction: dQ/dt = kA(T1 - T2)/L; series and parallel slabs combine like resistors.
Key points
- Compute the rate of heat conduction through composite slabs.
- Apply Stefan's and Wien's laws to radiating bodies.
Common exam trap
Using the temperature in Celsius in Stefan's law.
Definitions
- Term
Conduction, Convection and Radiation
- Meaning
Heat travels by conduction (dQ/dt = kA dT/dx), by convection through bulk fluid motion, and by radiation (Stefan's law, P = e σ A T4).
- Term
Conduction, Convection and Radiation — explanation
- Meaning
Conduction dominates in solids, convection in fluids, and radiation needs no medium at all. Wien's law relates the peak wavelength to temperature, which is the basis of infrared thermography.
Learning objectives
Compute the rate of heat conduction through composite slabs.
Apply Stefan's and Wien's laws to radiating bodies.
Formulae
- Key point
Conduction: dQ/dt = kA(T1 - T2)/L; series and parallel slabs combine like resistors.
- Key point
Stefan-Boltzmann: P = e σ A T4; net exchange uses T4 - T04.
- Key point
Wien's law: λmax T = constant.
Prerequisites
PHY-U3-THR-T1-S1-C2
Common mistakes
Using the temperature in Celsius in Stefan's law.
Assuming radiation requires a medium.
Keywords
Conduction
Convection
Radiation
Practice preview
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