Question

What effect does increasing the wedge angle have on the spacing of interference fringes? If the wedge angle is too large, fringes are not observed. Why?

a. Increasing the wedge angle widens fringe spacing; too large an angle causes destructive interference.
b. Increasing the wedge angle narrows fringe spacing; too large an angle causes excessive dispersion.
c. Increasing the wedge angle narrows fringe spacing; too large an angle causes constructive interference.
d. Increasing the wedge angle widens fringe spacing; too large an angle causes light to bypass the wedge.

Answer 1

Increasing the wedge angle narrows the fringe spacing in interference patterns; if the angle is too large, the fringes blend together and cannot be resolved.

Step-by-step explanation:

Increasing the wedge angle in a setup for interference fringes has the effect of narrowing the spacing between the fringes. This happens because a larger wedge angle causes the path difference between the light waves reflecting off the upper and lower surfaces of the wedge to increase more rapidly as one moves away from the point of contact. If the wedge angle is too large, no fringes are observed because the spatial frequency of the fringes becomes so high that they are no longer resolvable by the observing instrument or eye.