# Homework Help: Which describes the interference at P? (Multiple Choice)

1. Apr 20, 2012

### McAfee

1. The problem statement, all variables and given/known data

In Young’s double-slit interference experiment, if the rays that reach point P on the viewing screen have a path length difference of 2.50 wavelengths, which describes the interference at P?

A. It is the central bright fringe.
B. It is the first dark fringe to either side of the central bright fringe.
C. It is the first bright fringe to either side of the central bright fringe.
D. It is the second dark fringe to either side of the central bright fringe.
E. It is the second bright fringe to either side of the central bright fringe.
F. It is the third dark fringe to either side of the central bright fringe.
G. It is the third bright fringe to either side of the central bright fringe.
H. It is the fourth dark fringe to either side of the central bright fringe.
I. It is the fourth bright fringe to either side of the central bright fringe.

2. Relevant equations

3. The attempt at a solution

My friend said he think the answer is D, but I was think F because 2.5 wavelength automatically put you in the third fringe then it is dark because it is at a minimum.

2. Apr 20, 2012

### collinsmark

I believe you are correct.