A double slit experiment is performed with monochromatic light. The separation between the slits is 1.150mm apart and an interference pattern is noticed on a screen 3.90m away. If the second fringe is 4.20mm from the central fringe, what wavelength and colour is the light? (You need to google wavelengths

Answer 1

Isn't this a standard formula? What is it about this you do not understand?

Answer 2

x=kLλ/d
λ=xd/kL=
=4.2•10⁻³•1.15•10⁻³/3.9•2=6.2•10⁻⁷ m
red