# The vibration direction of light wave

1. Jun 10, 2009

### ltd5241

If the light move from left to right, what's the vibration direction of light wave? up-down or front-back or some other ways?

2. Jun 10, 2009

### maverick_starstrider

well, in a classical picture, light is an oscillating magnetic wave reinforcing an oscillating electric wave (or vice versa) which is perpendicular to it. However, the polarization of light determines its orientation. See http://en.wikipedia.org/wiki/Polarization

3. Jun 10, 2009

### ltd5241

4. Jun 10, 2009

### Andy Resnick

5. Jun 10, 2009

I think he means that sunlight appears to come from more than one source spots, so how can it just oscillate in one direction?

6. Jun 10, 2009

### Staff: Mentor

7. Jun 11, 2009

### Andy Resnick

I'm not sure what the OP means... as for your interpretation, who claimed sunlight was polarized?

8. Jun 11, 2009

### ltd5241

water vibrate up-down right? what about the one colour normal light?

9. Jun 11, 2009

### Bob S

The direction of a photon (radio wave, microwave, IR radiation, visible light, UV radiation, x-rays, gamma rays, synchrotron radiation, etc.) is given by the Poynting vector, P = E x H.. Since it is a vector cross product. Both E and H are orthogonal to P.

10. Jun 12, 2009

### ltd5241

Do you mean the direction is random and vibrate in all direction which is orthogonal to the light travel direction?

11. Jun 12, 2009

### Bob S

Precisely. For all unpolarized light, the direction of vibrations of the electric and magnetic fields is random, as long as they are orthogonal to the direction of travel. For individual light "photons", the individual quanta of light, the electric and magnetic vibrations are orthogononal to each other, and both are orthogonal to the direction of travel. But light is composed of billions of photons, and for unpolarized light, they are all randomly oriented.

12. Jun 13, 2009

### ltd5241

That's what i want.And thank you all who answer my question!