Thermodynamics alevel physics

Specific heat capacity (c)

The energy required to raise the temperature of 1 kg of a substance by 1 K without a change of state.

Specific latent heat (L)

The energy required to change the state of 1 kg of a substance at constant temperature.

Specific latent heat of fusion (L_f)

The energy required to change 1 kg of a solid into a liquid at constant temperature.

Specific latent heat of vaporisation (L_v)

The energy required to change 1 kg of a liquid into a gas at constant temperature.

Internal energy

The sum of the randomly distributed kinetic and potential energies of the particles in a substance.

Absolute zero (0 K)

The temperature at which the average kinetic energy of the molecules of a substance is zero.

Ideal gas

A theoretical gas that obeys the equation pV=NkT under all conditions.

Boltzmann constant (k)

1.38×10^(-23) " " 〖"J K" 〗^(-1); links the microscopic motion of molecules to the macroscopic temperature.

Root mean square (r.m.s.) speed (c_rms)

The square root of the mean of the squares of the molecular speeds in a gas.

Black body radiator

An idealised body that absorbs all incident radiation and emits the maximum possible radiation at every wavelength.

Luminosity (L)

The total power radiated by a star or source in all directions.

Intensity (I)

The power per unit area received at a distance from a source.

Thermistor

A resistor whose resistance decreases as temperature increases (negative temperature coefficient).

Thermostat

A control device that uses a thermistor in a circuit to maintain temperature by switching a heater or cooler on/off.