Light Waves
Middle School
Definition
Electromagnetic waves, including visible light, that carry energy and can travel through a vacuum. Light waves can be reflected, refracted, and absorbed, and the visible spectrum is only a small part of the full electromagnetic spectrum.
Worked examples
\(c = 3.0 \times 10^8 \) m/s\(\)
Light waves travel at this constant speed through a vacuum, the fastest speed possible in the universe.
Visible light (red to violet) is only \(400\)–\(700 \) nm\(\) of the full spectrum.
The electromagnetic spectrum includes radio waves, microwaves, infrared, visible light, UV, X-rays, and gamma rays.
A prism refracts white light into a rainbow because each wavelength bends differently.
Refraction separates the colors because different frequencies travel at slightly different speeds through glass.
Common mistakes
- Light waves need air or a medium to travel. → Light waves can travel through a vacuum. Unlike sound, light is an electromagnetic wave and does not require a physical medium.
- Visible light is most of the electromagnetic spectrum. → Visible light is a tiny portion of the full electromagnetic spectrum. Visible wavelengths are only about 300 nm wide; radio and infrared span much larger ranges.
- Reflection and refraction are the same thing. → Reflection bounces light off a surface; refraction bends light passing into a new medium. Reflection happens at a boundary, refraction happens when light enters and slows down or speeds up.
Where you'll use it next
You'll use light waves when studying optics, lenses, and mirrors in physics, understanding photosynthesis and vision in biology, and exploring technologies like fiber optics, lasers, and astronomy.
See also
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026