Energy (thermal)

Thermal energy is the kinetic energy (E) of vibrating and colliding atoms in a substance, which is experienced as heat. The Austrian physicist Ludwig Eduard Boltzmann (1844 – 1906) showed that the average kinetic energy is equal to:

energy (E) = ½ k_B T

per degree of freedom of motion. Here, k_B = 1.380,649×10^-23 J/K is Boltzmann's constant and T is the absolute temperature expressed in kelvin (K).

At room temperature, the value of k_BT is about 25 meV. Neutrons with such an energy are called thermal neutrons. They are used for neutron activation.

Related quantities

• constant (Boltzmann)
• energy
• energy (electrical)
• energy (mass)
• energy (mechanical)
• energy (photon)
• heat
• power
• temperature