# Problem 14-10 Double Slit

A laser beam with light of wavelength $638.2\; nm$ is used to check a manufacturer's claim that a double slit has a separation of $0.200\; mm.$ The distance to the screen is $3.00\; m$ and the measured distance from the central maximum to the middle of the fourth minimum is $33.2 \;mm.$ What is the measured slit separation?
[Ans. $0.202 \;mm$]

As usual we start with a good diagram. Which data set is correct?

Solution $d$ $x$ $N$ $L$
(A) $2.00 \times10^{-3} \; m$ ? $4$ $3 \;m$
(B) ? $33.2 \times 10^{-3} \; m$ $4$ $3 \;m$
(C) ? $2.00 \times 10^{-3} \; m$ $4$ $3 \;m$
(D) $33.2 \times 10^{-3} \; m$ ? $4$ $3 \;m$