# Young's Double Slit Problem

## Homework Statement

Light from a sodium lamp (\lambda \; =\;589\;{\rm nm}) illuminates two narrow slits. The fringe spacing on a screen 150{\rm cm} behind the slits is 4.0{\rm mm} .

## Homework Equations

I think I should use: d*(y/L) = m(λ)

## The Attempt at a Solution

I did: d = 1(5.89e-7)*(1.5/.0044)
I changed everything to meters so later I can convert to mm.

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Simon Bridge
Homework Helper
Light from a sodium lamp ##\lambda \; =\;589{\rm nm}## illuminates two narrow slits. The fringe spacing on a screen ##150{\rm cm}## behind the slits is ##4.0{\rm mm}##
... presumably you want to find the slit spacing?
I think I should use: d*(y/L) = m(λ)
If you are unsure, sketch the setup and use geometry.

There are special conditions for the use of that equation - do you know what they are?
(If not, go back to the geometry.)
I did: ##d = (1)\cdot(5.89\times 10^{-7})\cdot(1.5)/(0.0044) ##
I changed everything to meters so later I can convert to mm.
... or you could just convert everything to millimeters right at the start?

So far so good - so... did you have a question?

Yeah, I figured it out. I think I was probably just entering things in my calculator strangely.

Thankya ^^

Simon Bridge