WavelengthToEnergy
Convert any photon wavelength to energy in joules and electronvolts using Planck's equation E = hc/λ. Free online physics calculator with interactive charts and breakdowns.
About This Calculator
The Wavelength to Energy Calculator converts any photon's wavelength into its corresponding energy using Planck's equation E = hc/λ. This fundamental relationship in quantum mechanics shows that electromagnetic radiation carries energy in discrete packets called photons, with energy inversely proportional to wavelength. Students, researchers, and professionals in physics, chemistry, optics, and photonics use this conversion for spectroscopy, quantum mechanics problems, laser design, and solar energy analysis.
The calculation uses Planck's constant (h = 6.62607015 × 10⁻³⁴ J·s) and the speed of light (c = 299,792,458 m/s), both CODATA-recommended values. The calculator supports wavelength units from nanometers to kilometers and displays results in joules (J), electronvolts (eV), frequency (Hz), and wavenumber (m⁻¹). A breakdown table and interactive charts (bar and pie) give you a complete view of the photon's physical properties.
Understanding the wavelength-energy relationship is essential across many fields: spectroscopy identifies materials by their absorption/emission spectra; solar energy analysis depends on the energy distribution of sunlight across wavelengths; medical imaging (X-rays, PET scans) relies on high-energy photons; and telecommunications uses specific infrared wavelengths with known photon energies for fiber-optic transmission.
Visible light reference: Violet (~400 nm, 3.10 eV), Blue (~475 nm, 2.61 eV), Green (~510 nm, 2.43 eV), Yellow (~570 nm, 2.17 eV), Red (~650 nm, 1.91 eV). Try entering these wavelengths to see the corresponding photon energies!
Frequently Asked Questions
How do you convert wavelength to energy?
Use Planck's equation E = hc/λ where h is Planck's constant (6.626 × 10⁻³⁴ J·s), c is the speed of light (299,792,458 m/s), and λ is the wavelength in meters. The result is the photon's energy in joules. To convert to electronvolts, divide by 1.602 × 10⁻¹⁹.
What is Planck's equation?
Planck's equation (E = hf) states that a photon's energy is directly proportional to its frequency. Combined with the wave equation c = fλ, it becomes E = hc/λ, allowing energy calculation from wavelength.
What units does this calculator support?
This calculator supports nanometers (nm), micrometers (μm), millimeters (mm), centimeters (cm), meters (m), and kilometers (km). Select your unit from the dropdown and enter the wavelength value.
What is a photon?
A photon is a quantum of electromagnetic radiation, the fundamental particle of light. It carries energy proportional to its frequency and has zero rest mass. Photons exhibit both wave-like and particle-like properties.
How accurate is this wavelength to energy calculator?
This calculator uses the CODATA-recommended values for Planck's constant (6.62607015 × 10⁻³⁴ J·s) and the speed of light (299,792,458 m/s). Results are accurate to 4 significant figures, suitable for physics, chemistry, and engineering applications.
What is the relationship between wavelength and energy?
Wavelength and energy are inversely proportional — shorter wavelengths correspond to higher energy photons. For example, gamma rays have very short wavelengths and extremely high energy, while radio waves have long wavelengths and low energy.
What is an electronvolt (eV)?
An electronvolt (eV) is the energy gained by a single electron when accelerated through a potential difference of one volt. It equals 1.602 × 10⁻¹⁹ joules and is commonly used in atomic, nuclear, and particle physics.
How do you find frequency from wavelength?
Frequency is calculated as f = c/λ where c is the speed of light and λ is the wavelength. This calculator automatically computes the frequency along with the energy, giving you a complete picture of the photon's properties.