young's double slit

what does this experiment show

it is a two source superposition creating an interference pattern

why use last for this

monochromatic light therefore will all have the same wavelength so the diffraction will be the same and the light source is coherent

equation for young's double slit

wavelength = ax/dwhere a = slit separationx = fringe separation d = distance to wall

how to find 'a' from the diffraction grating

if 1000lines per cmdivide 1 cm by 1000 to find the slit separation

diffraction grating formula

nλ = dsinθwhere theta is the angle between the maxima and the zeroth order line n = the order of minima or maxima