# Homework Help: Two Slit Interference

1. Jul 20, 2008

### conniechiwa

1. The problem statement, all variables and given/known data
An optical two-slit experiment is setup with its slits separated by 40 X 10-3 cm and produces a second order maximum at an angle of 0.09 degrees. What would the wavelength of the light need to be if we kept the position of the second order maximum the same, but increased the slit separation of 63 X 10-3 cm?

2. Relevant equations
wsinϑ=mλ

3. The attempt at a solution
630000nm*sin0.09=2λ
λ=494.8nm

2. Jul 20, 2008

### Kurdt

Staff Emeritus
I agree with you. Does the system want it in any other units?

3. Jul 20, 2008

### Redbelly98

Staff Emeritus
Two things occur to me:

1. Do they mean the final slit separation is 63 X 10-3 cm, or is that amount to be added to the original 40 X 10-3 cm?

2. Perhaps they are expecting an answer rounded to the nearest 1 nm?

4. Jul 20, 2008

### conniechiwa

It asks for the answer in nm. I tried adding the final slit separation to the original and it didn't work either.

5. Jul 20, 2008

### Redbelly98

Staff Emeritus
"63 X 10-3 cm" is a rather odd way to express a number or distance, since it's not proper scientific notation. You might double-check that this is actually what they say in the problem statement.

Proper scientific notation would be (for example)
6.3 x 10-2 cm.

6. Jul 20, 2008

### conniechiwa

Yeah it says 63 X 10-3 cm. I copied and pasted the question.

7. Jul 20, 2008

### Staff: Mentor

That highlighted word doesn't seem correct. Is it "to" or "by", by any chance?

8. Jul 20, 2008

### conniechiwa

No, it's "of".

9. Jul 20, 2008

### Staff: Mentor

Is this from a textbook?

10. Jul 20, 2008

### conniechiwa

It's online homework. Maybe it's glitched.

11. Nov 20, 2009

### Mrharlin

the equation you are looking for is;
sin$$\theta$$=n$$\lambda$$/2d

$$\lambda$$=(2d)sin$$\theta$$/n

"two-slit experiment is setup with its slits separated by 40 X 10-3 cm"
--this being two-slit means it is 2d

12. Nov 21, 2009

### Staff: Mentor

All you've done is taken the standard formula and renamed the slit separation 2d instead of the usual d.