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## anonymous 3 years ago Ok so on this what do I do (Please don't give me the answer I just want to know what I need to do on it) Medical X-rays, with a wavelength of about 10^-10m, can penetrate completely through your skin. Ultraviolet rays, which cause sun burn by penetrating only the top level of skin, have a wavelength about 1000 times the wavelength of an X-ray. find the wavelength of ultraviolet rays. Show your work.

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1. terenzreignz

It seems too simple, but, you just do what the problem says, and, it seems it *explicitly* says '1000 times the...' which would normally indicate that you multiply by a factor of 1000.

2. anonymous

So I multiply 10^-10 by 1000?

3. terenzreignz

I would think so.

4. anonymous

So its 100,000,000,000,000?

5. terenzreignz

Okay, so, what do you think $\Large 10^{-10}$means?

6. anonymous

I did 10^-10 * 1000 and got 100,000,000,000,000

7. terenzreignz

How? Why? lol

8. anonymous

Well I asked if I multiply 10^-10 * 1000 and you said you think so :P

9. terenzreignz

Yes, that's true, but how exactly did you arrive at your answer? $\Large \left.\begin{matrix}10^{-10}\cdot 1000&=&100 \ 000 \ 000 \ 000 \ 000\\&\color{red}?&\end{matrix}\right.$

10. anonymous

First I multiplied out 10^-10 and got 100,000,000,000 then I multiplied it by 1000 and got 100,000,000,000,000

11. terenzreignz

Hang on, why is $\Large 10^{-10}$equal to 100 000 000 000

12. anonymous

I multiplied it out

13. anonymous

...

14. anonymous

Am I not suppose to do that...

15. klimenkov

What is $$a^{-1}$$ ?

16. terenzreignz

Sorry... the problem here is that the exponent was negative... so it's not as straightforward as simply 'multiplying out'

17. terenzreignz

But first, @klimenkov asked you a question ^_^

18. anonymous

|dw:1377670025131:dw|

19. terenzreignz

Okay, now what about $\Large a^{-n}$

20. anonymous

|dw:1377670107287:dw|

21. anonymous

Now can we get back to the question sorry for the rush I just have a ton of work I have to get done tonight

22. terenzreignz

Okay... well, if you could do that with the 'a' What is $\Large 10^{-10}$ ?

23. klimenkov

Now, what is $$10^{-10}$$ ?

24. anonymous

|dw:1377670300729:dw|

25. anonymous

Was not thinking I have had so much going on today with school

26. terenzreignz

That's right :) Now multiply THAT to 1000. And let me take the liberty of reminding you that $\Large 1000 = 10^3$

27. anonymous

Ok so it equals 10^7

28. terenzreignz

No... it's the bottom exponent that's bigger...

29. terenzreignz

$\Large 10^{-10}\cdot 10^3$ First law of exponents... when you multiply, with same base, ADD the exponents.

30. anonymous

That's what I was doing...|dw:1377674852025:dw|

31. terenzreignz

Yes. That's right :D $\Large \frac1{10^7}=10^{-7}$

32. anonymous

Thanks :)

33. anonymous

Can you please help me on this one to? the wavelengths of visible light are between 3.8 * 10^-7m and 7.6 * 10^-7m. Are these wavelengths longer or shorter than those of ultraviolet rays? Explain On it do I need to simplify each scientific notation out and just put how I simplified them and put what one is bigger?

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