Question

What happens if i replace sodium vapour lamp with white light in newtons ring exp

Answer 1

Point 1 means that it is only the phase difference that is important in determining the throughgoing / reflected light for a monochromatic wave. So, all monochromatic waves, whatever their random phase, produce the same interference pattern. The angle between the incoming ray and the glass plate is 45 degree to make turns the light rays to 90 degrees and that's why the rays fall normally on the plano-convex lens. Finally forms circular rings.

Answer 2

Answer:

Refer to the attachment