A pair of narrow, parallel slits separated by $0\mathrm{.}250$ mm is illuminated by light from a green laser $($lambda $=546\mathrm{.}1$nm$)$ The interference pattern is observed on a screen $1\mathrm{.}20$ m away from the plane of

the slits. a$)$ Calculate the distance from the central maximum to the first bright region on either side.

$[2\mathrm{.}62$ mm$]$

b$)$ Calculate the distance between the first and second dark bands in the interference pattern.

$[2\mathrm{.}62$ mm$]$

c$)$ If the slits are now illuminated with red light $($lambda $=650$nm$)$ calculate the distance between the central maximum to the first dark band. $[1\mathrm{.}56$ mm$)$