# Homework Help: Electromagnetic spectrum

1. Feb 3, 2009

### stickplot

1. The problem statement, all variables and given/known data

What region of the electromagnetic spectrum contains wavelengths the size of an atom? (10^-10 meters) What frequency does this wavelength correspond to?

2. Relevant equations

velocity=wavelength(frequency)

3. The attempt at a solution

3x10^8/1x10^-10=f

i think i did everything right
but my answer keeps coming out to 3E18
which i dont think is right and i dont know what the unit would be (hertz, megahertz)

2. Feb 3, 2009

### mgb_phys

You need to look up the words, check what wavelengths correspond to x-ray, gamma-ray etc.

You need to put units in your equation.
speed (m/s) = wavelength (m) * frequency (1/s )
So the answer( frequency) is in 1/s = Hz.
Then you just have to know what the word is for 10^18 - but nobody uses the words for this band anyway.

3. Feb 3, 2009

### stickplot

there electromagnetic waves and now im pretty sure its hertz, the only thing im not sure about is my answer because it seems odd, really long

4. Feb 3, 2009

### mgb_phys

10^18 is exa-hertz, but I had to go and look it up because nobody uses it!
You can specify an electromagnetic wave by energy, wavelength or frequency interchangeably - because the speed of light is always the same you can always convert form one to another.

For historical and techncial reasons, people working in x-ray and gamma rays tend to use energy (in eV), then from UV through visible to IR they use wavelength.
In microwaves it overlaps, with communications engineers using frequency and radar people using wavelength
Then in radio we generally use frequency and finally in low frequency radio (ie long wave) we use wavelength again!

5. Feb 3, 2009

### stickplot

o ok well this is what i got for frequency 3x10^18, but ive looked at some ultraviolet spectrums and i dont know where this frequency would be located in the spectrum.

6. Feb 3, 2009

### mgb_phys

Wavelengths of 10nm-0.01nm , or frequency 10^16 - 10^19 are x-ray

7. Feb 3, 2009

### stickplot

o ok.. i had forgoten to swith to nanometers.... thank you very much