Photon Energy Calculator
Calculate photon energy from wavelength in nanometers.
Photon Energy Formula
E = hc/λ, where h is Planck’s constant and c is the speed of light.
What Is Photon Energy?
A photon carries an amount of energy determined by its frequency or wavelength. Shorter-wavelength photons have more energy, while longer-wavelength photons have less. The calculator uses E = hc/λ and reports both joules and electron volts.
Example Calculation
For green light with a wavelength of 500 nm, photon energy is about 3.97 × 10⁻¹⁹ J, equivalent to approximately 2.48 eV.
Factors and Interpretation
Photon energy is inversely proportional to wavelength. Halving wavelength doubles energy. This relationship explains why ultraviolet photons are more energetic than visible-light photons and why radio photons carry much less energy individually.
Frequently Asked Questions
What is an electron volt?
An electron volt is a convenient microscopic energy unit equal to 1.602176634 × 10⁻¹⁹ joule.
Does light intensity change photon energy?
No. Intensity mainly changes the number of photons; individual photon energy depends on frequency or wavelength.
Why must wavelength be positive?
Physical wavelength is a positive distance, and zero would make the formula undefined.
Related Tools
Formula and Practical Limits
Photon energy is E = hc/λ, so shorter wavelengths correspond to higher photon energies. Use wavelength units consistently and distinguish energy per photon from energy per mole of photons.