Motion, Heat and Waves
Heat & Thermodynamics
14 minStudent plan
Where the wasted power in your circuit actually goes, how heat moves, and why every component has a temperature limit.
After this lesson you can
- Work out the heat needed to raise something's temperature
- Tell conduction, convection and radiation apart in a real design
- Say why a heatsink works
Heat is energy in transit
Temperature measures how energetic the particles in a body are on average. Heat is energy moving from a hotter body to a colder one. They are not the same thing: a spark from a grinder is at a very high temperature but carries almost no energy, which is why it is harmless.
Raising the temperature of a mass takes energy Q = mcΔT, where c is the specific heat capacity. Water's c is unusually high, at about 4200 J per kilogram per degree, which is why it is the standard coolant and why the sea moderates the climate.
The first law of thermodynamics is conservation of energy with heat included: the energy of a system changes by the heat added minus the work it does. Nothing is lost, it is only ever moved or converted.
In the full lesson
- Heat is energy in transit
- Three ways heat moves
- Thermal resistance and the second law
This lesson comes with the Student plan. The first module of Physics for Engineers is free.