# Measuring the relative frequency of light while traveling in different directions.

1. Oct 26, 2014

### grounded

Can anyone tell me if the following is correct?

Traveling directly towards a source of light at some constant speed, we will measure its frequency to be higher (compared to rest frequency) than what we would expect when using Newton’s laws. Just as traveling away from the source, we would measure its frequency to be a little lower than we would expect it to be.

Thanks!

2. Oct 26, 2014

### Staff: Mentor

Google for "Doppler effect" and "relativistic doppler effect".

The classical Doppler effect says that if you and the light source are moving towards one another (don't think of this as one of them at rest and the other moving) you will measure a higher frequency, and if you and the light source are moving apart you will measure a lower frequency.

Relativity adds an additional correction, the relativistic doppler effect.

3. Oct 26, 2014

### grounded

That's what I thought, just wanted to make sure. Thank you...