Interference effects are produced at point P on a screen as a result of direct rays from a 518 nm source and reflected rays off the mirror.If the source is 99 m to the left of the screen, and 1.15 cm above the mirror, calculate the distance y (in millimeters) to the first dark band above the mirror

Answer 1

I am not certain how the incident light is getting to the mirror. But remember the mirror itself does a 180 degree phase shift when it reflects.

Answer 2

there is a figure that accompanies this problem

the mirror is perpendicular to the screen where the mirror is the x-axis and the screen is the y-axis does that help because I am having trouble with this one