Well this is the pit, so perhaps someone here may be able to answer my question

Here it is:
Red shift, z = 0.203

This detected radiation originally must of been= 100nm

What is the detected radiation now?

Now i've attempted to do this with the ratio of:

z + 1 = )Wavelength now / wavelength then)

Which rearranges to give an answer of 1.203x10^7 or 0.012nm

But the book has the answer down as 0.1mm. Anyone able to point out where i've gone wrong?

I won't be able to because I don't understand anything you just said. Take comfort in the fact that you're a hell of a lot smarter than I am
0.1mm

Trust me man, I know!

DON'T PANIC! DON'T PANIC!
THEY DON'T LIKE IT UP 'EM!
the red shift wavelength you found was in nm when you did the first calculation? (i often forget this)
I Won't Let This Build Up Inside Of Me

Quote by FFTLxx

muhat gandy
+Sideways 8

Well thats me set ^^
The red shift value was given without units?
Which rearranges to give an answer of 1.203x10^7 or 0.012nm

i assume you did put in 'times ten to the minus 7'?
I Won't Let This Build Up Inside Of Me

Quote by FFTLxx

muhat gandy
+Sideways 8

Well thats me set ^^
well the x10^-7 is the standard form that the calculator put the answer to
i thought you had to convert units to mm when do any of these calcs. (i may be wrong it has been a long time)
I Won't Let This Build Up Inside Of Me

Quote by FFTLxx

muhat gandy
+Sideways 8

Well thats me set ^^
As long as it's in standard form it doesn't matter. I'm going to have a dig through my notes to see..
If the emitted wavelength is 100nm and red shift is 0.203, you're right and the observed wavelength is 1.2x10^-7 (or 120nm)

There's no way 0.1mm is the right answer, unless whatever is emitting the radiation is travelling at almost the speed of light, which would need special relativity.

You sure you've typed up the question right? Are you definitely looking at the answer to the right question? Something isn't right here...
Yep i've copied it down totally correctly. Which is why I was getting a tad frustrated about it, but I can't see anything else that would work so I presume the book is wrong

Cheers to everyone who chipped it, much appreciated