Answer:
Option b. Dark spot
Explanation:
Michelson interferometer gives the path difference of the light as path difference, d as twice the distance moved or covered by the mirror [tex]M_{2}[/tex], x and is given as:
d= 2x
Since, its an even multiple, we obtain a bright fringe
now, when the move half the distance, i.e., [tex]\frac{x}{2}[/tex]
Therefore, the path difference for half the distance [tex]\frac{x}{2}[/tex] is:
d = x
As it is clear that its an odd multiple which correspond to dark spot as the final image
