Propeties of light waves

[Drosera]

Hello,

 

Whenever I read about light waves (EM radiation), there is always mention of frequency and wavelength. No problem. But none of the things I have read have ever mentioned amplitude. How does amplitude fit into the basic model of the photon?

 

Thx, and take care!

[sanctus]

Very good question, I never asked myself that, but I'm sure there is a very easy answer, just onthe spot nothing comes to my mind. I'll talk to some people this afternoon then I should have the answer.

[cwes99_03]

Amplitude equals intensity. The power output of the light (amps) is a means of saying how much power the lightbulb puts out. Intensity is measured in candlepower.

 

Quick point. The energy of the wave and the amplitude of the wave are different, so don't get them confused.

 

great site here. http://hypertextbook.com/physics/waves/light/

[Drosera]

Cwes,

 

Hmm. I don't think you're post directly answered my question, though I did get one bit of information from the site you linked to.

 

Amplitude is inversely related to frequency.

 

Meaning with a higher frequency, a wave has a smaller amplitude, correct?

 

 

You said amplitude equals intensity. But this is confusing to me. I always thought intensity would be more a measurement of how many photons (how much light) is being sent out or seen. How can an individual wave be more intense than another?

 

And the Amps that you mention in reference to light bulbs actually refer to Amperes, a unit of measurement of electricity, not EM radiation.

 

Thanks for the info!

 

Take care!

[Tormod]

How can an individual wave be more intense than another?

 

According to this paper, amplitude is directly related to the probability of finding a particle at a certain point:

 

Electrons, photons, and the photo-electric effect

http://physics.bu.edu/~duffy/PY106/PhotoelectricEffect.html

 

The probability of finding a particle at a particular location, then, is related to the wave associated with the particle. The larger the amplitude of the wave at a particular point, the larger the probability that the electron will be found there. Similarly, the smaller the amplitude the smaller the probability. In fact, the probability is proportional to the square of the amplitude of the wave.

 

That two waves can have difference intensity is not difficult to understand - with sound waves, for example, the volume (intensity) of the wave is directly related to the amplitude. But I may be misinterpreting the issue here (and will promptly go to bed since it's 1am over here). :cup:

[Erasmus00]

You said amplitude equals intensity. But this is confusing to me. I always thought intensity would be more a measurement of how many photons (how much light) is being sent out or seen. How can an individual wave be more intense than another?

 

The amplitude of ONE photon represents the probability that the photon is in that area (or rather, the amplitude squared represents probability). When you have many photons given off from a light source, the amplitude can be thought of as representing the number of photons per second emitted.

-Will

[Drosera]

Hmmm....

 

 

I am almost totally in the dark when it comes to understanding quantum physics. I'd be lying if I said I completely understood what you folks have explained to me. I'll simply take your word for it, and hope that someday I read something that sparks the light of understanding for me. It's been known to happen. :cup:

 

Still, I've learned a little something, so thanks for taking the time to answer me.

 

Take care!