AI Tutor
Your Wi-Fi signal, a dentist's X-ray, and the green glow of a traffic light seem entirely different, but they are all identical forms of electromagnetic radiation traveling at the exact same speed through space.

Anatomy of a Light Wave

All light waves are oscillating electric and magnetic fields characterized by two core measurements: wavelength and frequency.
Wavelength (symbol Ξ»\lambda, the Greek letter lambda) is the physical distance between two consecutive crests or troughs, measured in meters (m\text{m}). Frequency (symbol Ξ½\nu, the Greek letter nu) counts how many wave cycles pass a fixed point each second, measured in Hertz (Hz\text{Hz} or sβˆ’1\text{s}^{-1}).
How do these two wave properties link together when light is moving across the universe?

The Speed of Light Equation

In 1865, Scottish physicist James Clerk Maxwell proved mathematically that all electromagnetic waves move through a vacuum at the speed of light, a universal constant denoted by c=3.00Γ—108Β m/sc = 3.00 \times 10^8\text{ m/s}.
Because speed equals distance divided by time, multiplying a wave's length (distance per cycle) by its frequency (cycles per second) gives its total speed: c=λνc = \lambda \nu
How do we apply this equation when laboratory instruments measure wavelength in nanometers?

Worked Example 1: Finding Frequency

A handheld red laser pointer emits light with a wavelength of 650Β nm650\text{ nm}. Let's calculate the frequency of this red light.