About how fast does light travel in a vacuum?
AnswerAbout 300,000 km per second
Light travels at about 300,000 kilometers per second.
Science · Facts & stats
Light facts & stats
7 fact-checked facts about the physics of light, color and optics, each with the reason behind it. 5 more are in today's round and join this page after it closes.
The basics
What splits white light into a spectrum of colors?
AnswerA prism
Different colors bend by different amounts as they pass through the prism.
Going deeper
Which visible color has the longest wavelength?
AnswerRed
Red sits at the long-wavelength end of the visible spectrum.
What does a light-year measure?
AnswerDistance
It is the distance light travels in one year.
What is a particle of light called?
AnswerPhoton
Light behaves as both a wave and a stream of photons.
Expert level
For what did Albert Einstein win his Nobel Prize in Physics?
AnswerExplaining the photoelectric effect
His 1921 Nobel cited his explanation of the photoelectric effect.
What is the approximate wavelength range of visible light?
AnswerAbout 380 to 750 nanometers
Human eyes detect light from roughly violet at 380 nm to red at 750 nm.
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