Light

Definition

Light is electromagnetic radiation that can be detected by the human eye. It behaves both as a wave and as a particle, known as photons.

5 Must Know Facts For Your Next Test

1. Light travels at approximately 299,792 kilometers per second in a vacuum.
2. The visible spectrum of light ranges from about 400 nm to 700 nm in wavelength.
3. Light can be dispersed into its component colors by passing through a prism, creating a spectrum.
4. The Doppler effect causes the redshift or blueshift of light depending on the relative motion of the source and observer.
5. Spectroscopy allows astronomers to determine the composition, temperature, density, and motion of celestial objects by analyzing their light spectra.

Review Questions

• What is the speed of light in a vacuum?
• How does light behave according to wave-particle duality?
• What information can astronomers gain from analyzing the spectrum of light from celestial objects?

Related terms

Electromagnetic Spectrum:

The range of all types of electromagnetic radiation including gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, and radio waves

Photon:

A quantum of electromagnetic radiation that exhibits properties of both particles and waves

Spectroscopy:

The study of the interaction between matter and electromagnetic radiation used to analyze characteristics such as composition and motion