Compared with a flashlight beam, what does a laser beam typically do?
AnswerStays narrow and spreads very little
Laser light is highly directional, so the beam stays narrow over long distances instead of spreading like a flashlight.
Science · Facts & stats
Laser facts & stats
7 fact-checked facts about lasers, each with the reason behind it. 5 more are in today's round and join this page after it closes.
The basics
Which kind of player reads music from a disc using a laser?
AnswerCD player
A CD player's laser reads tiny pits in the disc; a record player uses a needle.
Going deeper
What does LASER stand for?
AnswerLight Amplification by Stimulated Emission of Radiation
The name describes how atoms are stimulated to emit matching light that builds into a beam.
Which scientist first described stimulated emission, the principle behind lasers, in 1917?
AnswerAlbert Einstein
Einstein predicted stimulated emission decades before engineers used it to build lasers.
What color is the beam of a common helium-neon laser?
AnswerRed
Helium-neon lasers usually emit red light at a wavelength of about 633 nanometers.
Expert level
What material produced the light in the very first working laser?
AnswerA ruby crystal
Maiman's 1960 laser used a synthetic ruby rod lit by a flash lamp.
Scientists bounce lasers off reflectors left on the Moon by which missions?
AnswerApollo missions
Apollo astronauts left retroreflectors that let scientists measure the Earth-Moon distance very precisely.
Know these cold?Today's round is five questions like these, 20 seconds each. Your streak and level follow you to every arena.Play today's round