# Homework Help: Wavelength-easy problem

1. Apr 10, 2007

### map7s

Consider a commercial FM radio station that broadcasts at a frequency of 90.1 MHz. The associated electromagnetic radiation has a wavelength of ? m.

I'm pretty sure that this is a very easy problem, but for some reason, I don'ts really get it.

I was positive that I was supposed to use the equation c=wavelength*f

and I converted the frequency into Hz by multiplying by 1E6

and then I took the value of light (3E8) and divided it by my answer... is there something special about electromagnetic radiation the I failed to factor in?

2. Apr 10, 2007

### Hootenanny

Staff Emeritus
Nope, assuming you did the arithmetic correctly, your answer should be correct (around 0.3 meters).

3. Apr 10, 2007

### map7s

thank you so much !

4. Apr 13, 2007

According to de broglie relation lambda=h/mv ...which implies that velocity is inversely proportional to wavelength. But According to the reletion

V=n lambda ... velocity is directly proportional to wavelength...... How That diffenence is Causesd ? Am i going wrong Somowhere ?

5. Apr 13, 2007

### Dick

de broglie implies that velocity is proportional to lambda only for massive particles. Massless particles always travel at c. Where did you get V=n lambda? What is n?

6. Apr 14, 2007

Hey..

n is the frequency of the wave and V=n lambda is the basic Wave equation

7. Apr 14, 2007

### Dick

Ok, so de broglie says lambda of a massive particle is inversely proportional to the velocity at a fixed mass. V=n*lambda says the the lambda of any wave is directly proportional to velocity at fixed frequency. The two statesments refer to different classes of objects with different properties held fixed. They are two quite different statements.

8. Apr 16, 2007

okay. How it can be different ?de Broglie Equation deals with both particle and wave character ...and V=n*lambda equation deals with wave character.. Then how it can be different ?

9. Apr 16, 2007

### HallsofIvy

The wave character of a massive particle. The formula cited in this problem is for electromagnetic radiation- light.

10. Apr 16, 2007

### Dick

It's also important that different quantities are being held fixed in the two problems.