- #1
nonequilibrium
- 1,439
- 2
Homework Statement
"One microscope slide is placed on top of another with
their left edges in contact and a human hair under the right edge of the upper slide.
As a result, a wedge of air exists between the slides. An interference pattern results
when monochromatic light is incident on the wedge. At the left edges of the slides,
there is (a) a dark fringe (b) a bright fringe (c) impossible to determine."
Homework Equations
The Attempt at a Solution
So I know the answer is a, a dark fringe, but I don't understand why. First of all, when they say "is incident on the wedge", do they simply mean light is falling directly into the wedge? Or falling directly onto the upper slide, reaching the wedge and then hitting the bottom layer. I presume the latter.
So at the left they're touching each other. In my book it says there is a dark fringe because the only interference is the fact that the light hitting the upper surface has a 180° phase shift. This makes no sense, what would it interfere with? The fact the light gets a phase shift is not enough to cause blackness, right? I'm very confused...