# What is the wavelength

1. Apr 6, 2009

### shimizua

1. The problem statement, all variables and given/known data
An FM station broadcasts at 107.5 MHz. What is the wavelength of this wave?

2. Relevant equations
well i know that speed = frequency X wavelenght but if i dont know the speed then how can i find the length

3. The attempt at a solution
so i found out that the average length of a radio wave is about 3 m and tried it but it was the wrong answer. i am just confused how to find the wavelength with only the frequency.

2. Apr 6, 2009

### shimizua

oh so i think this is a second part to the question also. How long will it take for a message from Earth to reach the first astronauts who arrive on Mercury; assume Mercury is at its closest approach to Earth (9.17×107km)?

well i just did that distance 9.17x10^7 km and got it to m and then divided is by 3x10^8 which is the speed of light so what did i do wrong for that part?

3. Apr 6, 2009

### Hootenanny

Staff Emeritus
Nothing. You working is fine to either you have made a numerical error somewhere, or you have not entered the correct number of significant digits.
If you were to assume that the radio wave was travelling through space (which is a pretty good approximation for air), what would be its speed?

4. Apr 6, 2009

### shimizua

would i just use 3x10^8 m/s?

5. Apr 6, 2009

### shimizua

oh wait i think i did have my decimals mixed up for the problem about the time. haha thanks

6. Apr 6, 2009

### Hootenanny

Staff Emeritus
Sounds good to me.
No problem.

7. Apr 6, 2009

### shimizua

cool thanks it worked!