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Photon Energy, Wavelength & Frequency Calculator (Planck)

Calculate photon energy in electron-volts (eV) and Joules, frequency in Terahertz (THz), and wavelength in nanometers (nm) across the electromagnetic spectrum.

e.g. 532 nm (Green laser), 633 nm (HeNe red), 405 nm (Violet/UV)

Calculation Results

Photon Energy (eV): 2.33 eV Visible Spectrum (Green Light)
Photon Energy (Joules): 3.734 × 10⁻¹⁹ J
Frequency: 563.52 THz (5.64 × 10¹⁴ Hz)
Wavelength: 532.0 nm (5,320 Å)

About This Calculator

Calculate photon energy in electron-volts (eV) and Joules, frequency in Terahertz (THz), and wavelength in nanometers (nm) across the electromagnetic spectrum.

Frequently Asked Questions

What is Planck's equation for photon energy?

Planck's equation states E = h * f = (h * c) / λ, where E is photon energy in Joules, h is Planck's constant (6.626 x 10^-34 J·s), f is frequency in Hz, c is the speed of light (3 x 10^8 m/s), and λ is wavelength in meters.

What is the handy shortcut formula to convert wavelength to electron-volts (eV)?

In physics and optics, the convenient approximation is E (eV) ≈ 1239.8 / λ (nm). For example, a 532 nm green photon has an energy of approximately 1239.8 / 532 = 2.33 eV.

What is the photon energy range for visible light?

Visible light spans wavelengths from approximately 380 nm (violet, ~3.26 eV) to 750 nm (deep red, ~1.65 eV). Photons with energy above 3.1 eV enter the ultraviolet ionizing spectrum.

Why does frequency remain constant when light enters a different medium?

When light enters water or glass, its wavelength compresses and its propagation velocity slows (v = c / n), but its frequency and individual photon energy remain strictly constant.