# reflection grating

by VVill
Tags: grating, reflection
 P: 3 1. The problem statement, all variables and given/known data 2. Relevant equations d=1/N d*sin(theta)=m*(lambda) 3. The attempt at a solution d=1/1970 d=.0005076 .0005076*sin(theta)=2*600e-9 sin(theta)=.0000012/.0005076 arcsin(.002364)=.135º *sigh* 1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution
 HW Helper P: 1,542 One thing I see is that when you found d you didn't convert from cm to m, so you have inconsistent units in your equation.
 P: 3 d=.0005076cm = .000005076m .000005076*sin(theta)=2*600e-9 sin(theta)=.0000012/.000005076 arcsin(.2364)=13.7º Anything else I'm missing, because the answer is not 13.7º?
HW Helper
P: 1,542

## reflection grating

Why do you have m=2? If it is first order I would think it would be m=1.
 HW Helper P: 1,542 Are you sure you are using the right equation? I think the grating equation you are using is not quite right for the conditions of your problem. The one you are using is a special case where the angle of incidence is normal to the grating. You need to include the angle of incidence in your equation. So your equation would be d*(sin(theta(m)) - sin(theta(inc))) =m*lamda. where m = ±1 for first order maxima. Anyway see if that helps.

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