Question

A sheet of plastic (n = 1.56) covers one slit of a double slit (see the drawing). When the double slit is illuminated by monochromatic light (vacuum = 568 nm), the center of the screen appears dark rather than bright. What is the minimum thickness of the plastic?

Answers

bobpursley
all that is changed is the light is slowed in the plastic, so that there is a "distance" to be added to the plastic path (disance= deltaTimedelay*speedlight).

so at the center, the two beams are 180 deg out of phase, so it means 2*"distance" above= wavlength light.
what is time delay? well, it has to be
(n-1)thicknessplastic
2*speedlight*(n-1)thicknessplastic)=wavelength

chck my thinking.

Related Questions