Frequency Of Light
Calculate light frequency from its wavelength using f = c/λ. Get EM spectrum region, formatted results, and interactive charts with this free physics calculator.
About This Calculator
The Frequency Of Light Calculator computes the frequency of electromagnetic radiation based on its wavelength. Simply enter the wavelength in meters (or frequency in Hertz) and the calculator instantly returns the corresponding value using the speed of light constant, c = 299,792,458 m/s. This tool is ideal for physics students, optics researchers, and anyone working with electromagnetic spectrum analysis.
The core formula is f = c / λ (frequency equals speed of light divided by wavelength). Because the speed of light is a universal constant, knowing either the wavelength or frequency lets you determine the other. The calculator also classifies the result into the appropriate region of the electromagnetic spectrum — from gamma rays and X-rays through ultraviolet, visible light, infrared, microwaves, and radio waves.
How to Use
Enter any wavelength in meters (e.g., 5 × 10⁻⁷ for green light) or frequency in Hertz (e.g., 6 × 10¹⁴ for the same light). The calculator computes the missing value and displays a formatted result with the appropriate metric prefix (nm, THz, etc.) and the EM spectrum region. Results can be shared via the unique URL generated with your inputs.
Frequently Asked Questions
How do I calculate the frequency of light from its wavelength?
Divide the speed of light (299,792,458 m/s) by the wavelength in meters. For example, green light at 500 nm gives a frequency of about 599.6 THz using f = c/λ.
What is the formula for frequency of light?
The formula is f = c/λ, where f is the frequency in Hertz, c is the speed of light in vacuum (299,792,458 m/s), and λ is the wavelength in meters.
What is the frequency of visible light?
Visible light frequencies range from about 430 THz (red light at 700 nm) to 790 THz (violet light at 380 nm). The human eye perceives different frequencies as different colors.
How does wavelength relate to frequency?
Wavelength and frequency are inversely proportional. As wavelength increases, frequency decreases, and vice versa. This relationship is described by the formula λ = c/f.
What region of the EM spectrum corresponds to a given frequency?
The electromagnetic spectrum spans from gamma rays (above 30 EHz) to radio waves (below 300 MHz). Visible light occupies a narrow band between 430 THz and 790 THz.
Does the medium affect the frequency of light?
When light enters a medium, its speed and wavelength change, but its frequency remains constant. The color of light is determined by its frequency, not its wavelength in the medium.
Can I calculate the energy of light from its frequency?
Yes. The energy of a photon is E = hf, where h is Planck's constant (6.626 × 10⁻³⁴ J·s). Higher frequency light carries more energy per photon. For example, UV light is more energetic than infrared.