Energy of Light

The Photon Wavelength Energy calculator computes radiant energy in the Planck-Einstein relationship (E = h•ν) based on Planck's constant (h), the speed of light (c) and the wavelength of radiation (λ).

INSTRUCTIONS: Choose units and enter the following:

• (λ)  Wavelength of the radiation (light)

Photon Wavelength Energy (E): The calculator returns the energy in electron volts (eV). However, this can be automatically converted to other energy units via the pull-down menu.

The Math / Science

The Photon Energy formula  E = h•ν is used to compute radiant energy in  joules based on Planck's constant and a frequency of radiation in hertz.

Max Planck provided the photon energy equation which calculated energy in Joules from: his constant Planck's constant, and the frequency in Hertz.  The formula is:

    E = h•ν

where:

• E is the energy of the photon
• h is Planck's constant which is equal to 6.63e^-34 J*s
• v is the frequency in hertz.

However, this calculator converts the RF wavelength () to frequency, using the formula:

    ν = c/λ

where:

• ν is the frequency
• c is the speed of light 
• λ is the wavelength

Which combines to the formula for energy from wavelength:

    E = h • c / λ

History

In 1900, German physicist Max Planck provided the solution and launched a new era in physics with an idea that departed drastically from accepted concepts. Classical physics assumed that radiant energy was continuous; that is, it could be emitted or absorbed in any amount. Based on data from blackbody radiation experiments, Planck proposed that radiant energy could be emitted or absorbed only in discrete quantities, like small packages or bundles. Planck gave the name quantum to the smallest quantity of energy that can be emitted in the form of electromagnetic radiation. His theory gave rise to this equation.

Related Calculators:

• E = m•c² (mass/energy equivalent)
• m = E/c² (mass from energy)
• E = m•γ•c² (mass/energy equivalent not at rest)
• E = h•ν (Photon Energy from Frequency)
• E = h•c/λ (RF Energy from Wavelength)
• p = m•γ•v (Relativistic Momentum)
• c (Speed of light)
• γ ≈ 1 + v²/(2c²)
• KE≈m(1+v²/(2c²)-1)c²(Relativistic Kinetic Energy)

Reference

• en.wikipedia.org/wiki/Planck-Einstein relation