Also, some details about how you could find the frequency of an electromagnetic wave if you know the wavelength and the velocity of the electromagnetic wave.
2007-08-21 02:57:10 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Good question.
Lets say a big star is moving towards you at very, very high speed, speed close to the speed of light. Then the light from that star would appear more blue to you, it would be blue-shifted.
What happens is that the energy from the foward motion of the star is added to the energy of the electromagnetic waves eminating toward you from it, and that means that they are shifted shorter in wavelength.
The velocity of e-m waves is normally taken to be c, the speed of light, and so the relationship between wavelength and frequency is l = f/c.
When the velocity of e-m waves changes, say in water where they slow, then the wavelength lenghtens.
If that star were moving in the opposite direction, away from you, then its light would be red-shifted when it reached you. And of course it would still approach you at the same speed, c.
In the universe as we see it today, all the other galaxies are moving away from us. We can tell this because the light from them is red shifted.
And the further away they from us, the faster, more red shifted, they are, moving away even faster. This implies that the entire universe is expanding, a conclusion that most astronomers believe today.
2007-08-21 03:22:03 · answer #1 · answered by Radzewicz 6 · 0⤊ 1⤋
your questions is phased wrongly. dont understand what are you talking. light is an electromagnetic wave.
scientists have found out that the speed of an electromagnetic wave is 3 times 10 to the power of 8 m/s square
using the formula v=frequency multiply wavelength, you should be able to find the answer
electromagnetic waves are : gamma rays, x rays, uv rays, light , infra red, radio waves and microwaves
2007-08-21 10:53:38 · answer #2 · answered by destiny 3 · 0⤊ 1⤋
Electromagnetic waves *are* light, so they travel at c.
Speed, frequency, and wavelength are related by c = (wavelength)*(frequency).
2007-08-21 10:02:09 · answer #3 · answered by ZikZak 6 · 0⤊ 0⤋
Light is an EM wave. All em waves travel at light speed.
2007-08-21 10:05:32 · answer #4 · answered by ag_iitkgp 7 · 0⤊ 0⤋