Doomlearn
DE
Science & TechFact

The blue glow in a reactor pool comes from particles outrunning light.

Nothing beats light in a vacuum. In water, though, light crawls at only 75 percent of its speed, and charged particles from the reactor overtake it. The result is a kind of optical sonic boom: Cherenkov radiation, discovered in 1934, Nobel Prize in 1958. It radiates mostly in the ultraviolet; the visible remainder looks blue to you.

Useful: When you see a photo of a glowing blue pool, you are looking at electrons outpacing light in water.

Source: en.wikipedia.org

KernenergieLichtPhysik

Difficulty:

Question on this card

Why can particles in water be faster than light?

  1. Because Einstein was wrong
  2. Because light in water is slower than in a vacuum
  3. Because water accelerates particles
  4. Because reactors raise the speed of light
Show the answer

Correct: Because light in water is slower than in a vacuum

The limit applies to light in a vacuum. In water light travels at only about 0.75 c, and that can be overtaken.

Related cards

Keep reading

This card belongs to the topic Science & Tech. Every card is short, cites a source and can be saved – due ones come back by themselves later.

About Doomlearn · Projects · Legal notice · Privacy · Terms