# Diffracting grating?kinda confused?

1. Feb 28, 2009

### ibysaiyan

Diffracting grating???kinda confused?

1. The problem statement, all variables and given/known data
bits given:lamda(660nm) n=1,d=3.33, angle=?

2. Relevant equations
n(lambda)=dsin(theta)

3. The attempt at a solution

so from re-arranging the formula,etc i got this :6.66x^-7/3.33=sin(theta)
=>2x10^-7=sin(theta)
=>angle=1.14x10^-5(after inverse sin function) ? not sure if thats the answer =/

2. Feb 28, 2009

### The Bob

Re: Diffracting grating???kinda confused?

With what you're given, the answer (in degrees) seems fine to me.

The Bob

3. Feb 28, 2009

### ibysaiyan

Re: Diffracting grating???kinda confused?

k thanks alot cuz some1 told me that i got my d wrong, =) which is not now

4. Feb 28, 2009

### ibysaiyan

Re: Diffracting grating???kinda confused?

cant w8 to become astronomer =),need to work hard <.<,good stopped my gaming addiction.sorry if i wasnt allowed to type something out of context

5. Feb 28, 2009

### The Bob

Re: Diffracting grating???kinda confused?

As d was stated in the question, I can't see how it can be wrong. Good luck with your studies.

The Bob

6. Feb 28, 2009

### Redbelly98

Staff Emeritus
Re: Diffracting grating???kinda confused?

What are the units for this value of d? 3.33 meters would be awfully large for a diffraction grating!

7. Mar 1, 2009

### ibysaiyan

Re: Diffracting grating???kinda confused?

in the question was given that a diffraction grating is marked as 300lines/mm
a)find distance between slits (which i got 3.33 from 1/0.3)

8. Mar 1, 2009

### ibysaiyan

Re: Diffracting grating???kinda confused?

lol yea distance between slits 3.33m lol cant be hmm

9. Mar 1, 2009

### ibysaiyan

Re: Diffracting grating???kinda confused?

is probably mm

10. Mar 1, 2009

### The Bob

Re: Diffracting grating???kinda confused?

I've been away from units for too long. Yer, Redbelly98 is right. If it is 3.33mm then the answer is wrong. I apologise for assuming it was a 'plug-in-the-values' question. What's your final answer?

The Bob

11. Mar 1, 2009

### ibysaiyan

Re: Diffracting grating???kinda confused?

the answer i got is 3.33 for d .idk where i am messing things up.

12. Mar 1, 2009

### Redbelly98

Staff Emeritus
Re: Diffracting grating???kinda confused?

That is the key here. In 1 mm, there are 300 lines. So each line must be ____?

13. Mar 1, 2009

### ibysaiyan

Re: Diffracting grating???kinda confused?

hmm would it be: d=1/300000=3.33x10^-6

14. Mar 1, 2009

### Redbelly98

Staff Emeritus
Re: Diffracting grating???kinda confused?

If you include the correct units with that number, yes.

15. Mar 1, 2009

### ibysaiyan

Re: Diffracting grating???kinda confused?

k,ty =)