# Foo - Need chemistry/phiscis help

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View Full Version : Need chemistry/phiscis help

Hickeydog
10-28-08, 06:45 PM
These questions are starting to piss me off....anyways

Cobalt-60 is a radioactive isotope used to treat cancers of the brain and other tissues. A gamma ray emitted by an atom of this isotope has an energy of 1.33 MeV (million electron volts; 1 eV = 1.602e-19 J). What is the frequency (in Hz) and wavelength (in m) of this gamma ray?

I used the equation E=HC/lambda (E is energy, H is Plank's constant, 6.63e-34, C is the speed of light, 3.0e8, and lambda is the wavelength.) I solved for lambda and got HC/E=lambda. Plug and chug and I get 1.2e-6m. Only problem is, that's not the correct answer. So what am I doing wrong?

Edit: Okay. First problem was that I didn't convert 1.33 MeV to J. So I re-did the calculations with 2.13066e-19J and came out with 9.3e-7m and that's still wrong. So my question still stands.

Lamplight
10-28-08, 06:46 PM
First I think you may need some spelling help. :innocent:

Sorry! I couldn't help myself! :D

Hickeydog
10-28-08, 06:51 PM
what was spelled wrong?

Tude
10-28-08, 06:51 PM
First I think you may need some spelling help. :innocent:

Sorry! I couldn't help myself! :D

Me too :innocent:

(and I can't help with the phiscis question either)

;)

Tude
10-28-08, 06:52 PM
what was spelled wrong?

physics.

Well, unless it's Fizz-ics or Phizycs or ... :D

Hickeydog
10-28-08, 06:53 PM
thanks. figh1fight1:crash:figh1fight1:fight::notamused:

Hickeydog
10-28-08, 06:57 PM
never mind. I figured the ****ing thing out.

Tude
10-28-08, 06:59 PM
LOL (and glad ya figured it out)

Hickeydog
10-28-08, 07:03 PM

ggggggrrrrrrrrrrrrrrrrrrrrrr

*starts looking for murder weapons*

Tude
10-28-08, 07:05 PM
slips out the side door ... - it wasn't me ...

Alfster
10-28-08, 07:14 PM
After seeing the title, with likely the worst, incorrect spelling I've seen yet for 'physics', I had to check to see if this was a joke thread. It wasn't :eek:

Alfster
10-28-08, 07:15 PM
Wait, did you say you were about to kill someone? Please disregard my last post.

ehidle
10-28-08, 07:16 PM
These questions are starting to piss me off....anyways

Cobalt-60 is a radioactive isotope used to treat cancers of the brain and other tissues. A gamma ray emitted by an atom of this isotope has an energy of 1.33 MeV (million electron volts; 1 eV = 1.602e-19 J). What is the frequency (in Hz) and wavelength (in m) of this gamma ray?

I used the equation E=HC/lambda (E is energy, H is Plank's constant, 6.63e-34, C is the speed of light, 3.0e8, and lambda is the wavelength.) I solved for lambda and got HC/E=lambda. Plug and chug and I get 1.2e-6m. Only problem is, that's not the correct answer. So what am I doing wrong?

Edit: Okay. First problem was that I didn't convert 1.33 MeV to J. So I re-did the calculations with 2.13066e-19J and came out with 9.3e-7m and that's still wrong. So my question still stands.

You're missing a factor of 1 million.

if 1eV = 1.602E-19, then 1.33 MILLION eV = 1.602E-19 * 1.33E+06 = 2.13066E-13, not -19.

jsharr
10-28-08, 08:00 PM
I think I may submit this thread to fail blog.

jschen
10-28-08, 10:58 PM
Carrying units along in your calculations would have immediately revealed the problems. One should always carry units.