# Double slit interference

1. Aug 19, 2010

### svitak

1. The problem statement, all variables and given/known data

Two slits are separated by 0.320 mm. A beam of 500-nm light strikes the slits, producing an interference pattern. Determine the number of maxima observed in the angular range -30 degrees < theta < 30 degrees.

2. Relevant equations

d*sin(theta) = m*(lambda)

3. The attempt at a solution

(.32)sin(30)/.0005mm = m
m=320

so there are 320 maxima in 30 degrees. and thus 640 in this total range. is that right?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Aug 19, 2010

### theJorge551

Seems fine to me.

3. Aug 19, 2010

### hikaru1221

There is a problem.
What if it's from -0.001 degrees to 0.001 degrees? Find m corresponding to that case and you will find out what you missed

4. Aug 19, 2010

### theJorge551

I think your comment has weight...but the range of visibility of this diffraction pattern are already set in place...namely between 30 and -30 degrees. OP, correct me if I'm mistaken in my interpretation of your problem statement, please.

5. Aug 20, 2010

### svitak

I'm not entirely sure what you are getting at. But, I'm pretty sure it is meant to be strictly limited to 30 and -30.

6. Aug 20, 2010

### hikaru1221

No, I mean, what if the question asks for the number of maxima in another range. Just replace -30 with -0.001 and 30 with 0.001, solve the problem again, and you will see why.