Interference Pattern: Find # Bright Fringes w/483nm Light

[tomrja]

Homework Statement

Two slits are illuminated with 483 nm light. If the slits are separated by 0.84 mm and each have a width of 0.07 mm, about how many bright interference fringes will be seen in the region of the central diffraction maximum?

Homework Equations

2nd = (m + 1/2)\lambda
a sin(theta) = m\lambda
ybright = (m lambda L)/d

The Attempt at a Solution

I don't think that the first equation applies to this problem, but I put it in there anyway just in case. The other formula is labeled as the destructive interference. I don't exactly know what formula to use or what to solve for. Any advice is appreciated.

 

[vela]

It would help if you understood to what situations each equation applies and what it tells you. Then you'll know if each would apply to the described set-up. In other words, you need to refine your thinking a bit more than "this problem involves interference" and "this equation was on a page in the book talking about interference."

Also, what do you think is going on in the problem? In other words, if you set this experiment up, what would you think will be on the screen? What would you measure on the screen to answer the question posed?