# What is energy density of photon?

## What is energy density of photon?

This represents the number of photons per unit volume per unit energy at energy E. This energy density is a factor in thermal radiation from a cavity.

What is the energy of photon gas?

Thus for example, the average energy per photon in a photon gas is 2.7 kT, compared with 1.5 kT for the ideal gas. Similarly, the pressure P of the photon gas is 0.9 NkT/V compared with NkT/V for the ideal gas.

What is difference between photon gas and ideal gas?

The essential difference between the photon gas and the ideal gas of molecules: for an ideal gas, an isothermal expansion would conserve the gas energy, whereas for the photon gas, it is the energy density which is unchanged, the number of photons is not conserved, but proportional to volume in an isothermal change.

### What do you mean by photon gas?

In physics, a photon gas is a gas-like collection of photons, which has many of the same properties of a conventional gas like hydrogen or neon – including pressure, temperature, and entropy. Photons are part of a family of particles known as bosons, particles that follow Bose–Einstein statistics and with integer spin.

What is energy density formula?

U = E/V. Dimension. In physics, energy density is the amount of energy stored in a given system or region of space per unit volume.

How many joules is a photon?

It should not surprise us that the energy of a single photon is small. It is also useful to calculate the number of photons in a Joule of energy. This is just the inverse of the energy per photon, and gives 3.2×1018 photons per Joule.

## What is the maximum energy of a photon?

, that is, energy of a photon is inversely proportional to the light’s wavelength. – Hence, the light having the lowest wavelength will have maximum energy. – On the basis of wavelength, red has the maximum wavelength, then green, then comes blue and lastly violet. Therefore, violet has the maximum energy.

Why is the chemical potential of a photon has zero?

And the energy to create any particle, relativistically, is easily seen as the mass-energy. And a photon has no mass. So its mass-energy is zero. Thus the chemical potential to add a photon is also zero.

How do you find the density of a photon?

The number density of blackbody photons with wavelength between λ and λ + dλ is given by dividing the blackbody energy uλ dλ in the wavelength range by the photon energy hν = hc/λ: nλ dλ = uλ hc/λ dλ = λuλ hc dλ.