Question about how lasers work?

[tommysmith]

Today in science class, my teacher was using a laser to point to the different elements on the periodic table. I was noticing that you couldn't see the light beam going to the wall, only when it hit the wall.

 

[udanis]

Today in science class, my teacher was using a laser to point to the different elements on the periodic table. I was noticing that you couldn't see the light beam going to the wall, only when it hit the wall.

Your question is?

 

[IsaacT]

The reason you don't see the beam in the air is because:

A. the laser was probably <5mW, so visibility is not very high at all.
B. There was probably no visualizers like smoke in the air to bring out the beam.

When lasers are directed through the air, the beams are only able to be seen when the laser hits dust and other stuff in the air. And even then, the Laser must be powerful or you won't see anything.

 

[Garoq]

Today in science class, my teacher was using a laser to point to the different elements on the periodic table. I was noticing that you couldn't see the light beam going to the wall, only when it hit the wall.

Here's some good reading:

Rayleigh scattering - Wikipedia, the free encyclopedia

 

[Cyparagon]

When you turn on a light bulb, it lights up the room, not the air. Same concept.

 

[mod101]

When a laser travels through the air, it interacts with air molecules and gets "scattered" in random directions. With a low powered laser these random scatterings dont have enoug energy to excite your eyes. when the power increase, enough of the random scattering reaches your eye and you view this as a beam.
basics of rayleigh scattering