Young's double-slit experiment - Bright fringes occurring

[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:

A) π/4, B) π/2 C) 3π/4 D) π E) 2π
The correct answer is D.

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.)

 

[Steve4Physics]

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:

A) π/4, B) π/2 C) 3π/4 D) π E) 2π
The correct answer is D.
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.)

Yes - you are correct (answer E). A difference of 1 wavelength corresponds to a phase difference of $2\pi$ radians. The 'official' answer is wrong.

 

[hidemi]

Yes - you are correct (answer E). A difference of 1 wavelength corresponds to a phase difference of $2\pi$ radians. The 'official' answer is wrong.

Thanks for clarifying!