Understanding Wavelengths and Fringes

[hidemi]

Homework Statement

In a Young's double-slit experiment the center of a bright fringe occurs wherever waves from the slits differ in phase by a multiple of:

the answer is 兀.

Relevant Equations

d * Δy/L = m*λ

I think the answer is E because each bright fringe is differed by a wavelength, in other words, one wavelength is equal to 2π.
(For example, the first bright fringe is d * Δy/L = 1*λ.)

 

[berkeman]

Homework Statement:: In a Young's double-slit experiment the center of a bright fringe occurs wherever waves from the slits differ in phase by a multiple of:

the answer is 兀.
Relevant Equations:: d * Δy/L = m*λ

I think the answer is E because each bright fringe is differed by a wavelength, in other words, one wavelength is equal to 2π.
(For example, the first bright fringe is d * Δy/L = 1*λ.)

I'm thinking the correct answer is "A". Or maybe "G", but I can't be sure. (Because the multiple choice answers are not visible in your post...)

 

[hidemi]

I'm thinking the correct answer is "A". Or maybe "G", but I can't be sure. (Because the multiple choice answers are not visible in your post...)

sorry ,The multiple choices are :
A) π/4, B) π/2 C) 3π/4 D) π E) 2π
The correct answer is D, however I think it should be E.