Crave the Wave B

[John Richardsim]

Okay, let's get the Question Marathons populated (starting here).

What is an oscillation? How is an oscillation related to a wave?

[ampy1234567]

Answer (Click to Show Hidden Text)

An oscillation is a regular periodic motion. Oscillations are related to waves in that waves are a type of oscillations.

Hm not sure too sure about second part

[John Richardsim]

Answer (Click to Show Hidden Text)

An oscillation is a regular periodic motion. Oscillations are related to waves in that waves are a type of oscillations.

Hm not sure too sure about second part

Yeah, I'll accept it. Your turn!

[ampy1234567]

Question (Click to Show Hidden Text)

Say that galaxy A is actually blue, but appears red from planet B. If planet B is moving at a rate of 0.2c southward and galaxy A is moving at a rate of k*c northward, find k. Assume that the wavelengths of red and blue are 750 and 450 nm respectively, and ignore any possible effects of relativity.

[Adi1008]

Question (Click to Show Hidden Text)

Say that galaxy A is actually blue, but appears red from planet B. If planet B is moving at a rate of 0.2c southward and galaxy A is moving at a rate of k*c northward, find k. Assume that the wavelengths of red and blue are 750 and 450 nm respectively, and ignore any possible effects of relativity.

I thought I did this question but it looks like I forgot to submit it or something :/

Anyways, here's what I got:

I have no idea what I'm doing (Click to Show Hidden Text)

[b] k = 1/3[/b]. Work is here: http://imgur.com/JDUcEoF I got different answers doing it different ways, so it could be wrong T_T

[ampy1234567]

Yeah that's right
I had the same work as you BTW

[Adi1008]

Yeah that's right
I had the same work as you BTW

When light passes through a different medium and slows down or speeds up, does the frequency or the wavelength change? Why?

[ampy1234567]

Answer? I also have no idea what I'm doing (Click to Show Hidden Text)

The wavelength changes. This is because the wave equation, which is (lamba)*f=speed, shows that a change in speed will cause changes in the frequency and/or the wavelength. Since the frequency remains constant (otherwise you would probably have a large "pile-up" of waves near the interface), wavelength therefore must change.

[amydata123]

no one has done a question for a while, so.........

8. As observed from the Earth, the light from a star is shifted
toward lower frequencies. This is an indication that the
distance between the Earth and the star is
(1) decreasing (3) constant
(2) increasing

[ampy1234567]

Answer (Click to Show Hidden Text)

2: Increasing