Photon Energy from Wavelength

The Photon Energy from Wavelength calculator compute the energy of a photon based on Planck's constant (h), the speed of light (c) and the wavelength of the photon ( λ).

INSTRUCTIONS: Choose units and enter the following:

• (λ) Wavelength of Photon

Energy of Photon (E): The calculator returns the energy in Joules or electron volts for very small values.  However, these can be automatically converted to compatible units via the pull-down menu.

The Math / Science

The energy of a photon depends only on its wavelength.  The formula for the energy of a photon is:

          E= h•c / λ

where:

• E = energy of the photon
• h = Planck's constant 
• c = speed of light ( 2.998 × 10⁸ m/s)
• λ= wavelength of the light

Note the following relations are also true:

`f = c/λ`

`f = E/h`

`E = (h⋅c) /λ` 

`λ = (h⋅c)/E`

`E = h * f`

where:

• E = energy of light
• f = frequency
• h = Planck's Constant
• c = Speed of Light in a vacuum 

Energy Calculators

• Kinetic Energy:                                    `KE= 1/2 *m * v^2`
• Kinetic Energy (change of velocity):    `KE = 1/2*m*(V_1-V_2)^2`
• Relativistic Kinetic Energy:                    `E_K = (m*c^2)/sqrt(1 - v^2"/"c^2") - m*c^2`
• Potential Energy:                                  `U(y) = m*g*y`
• Potential Energy of Gravity (two bodies):   `U(G) = - (G*m1*m2)/r`
• Nuclear Binding Energy:                       `E = m*c^2`
• Quantum Energy (Planck's Equation):   `E = h*f`
• Energy of a Particle in a Box:                `E_n=(n^2h^2)/(8mL^2)`
• Molecular Kinetic Energy:                      `KE = 3/2 * k_B *T`
• Electrostatic Potential Energy:               `E_(el) = k_e * (Q_1*Q_2)/d`
• Photon Energy from Wavelength:          `E = (h*c)/lambda`
• Heat Energy to Change Material Temperature:  `Q = C * m *DeltaT`

Astronomy Calculators