# Young's double-slit experiment - Bright fringes occurring

• hidemi
In summary, the correct answer for the center of a bright fringe in a Young's double-slit experiment is E, as each bright fringe is differed by a wavelength, or a phase difference of 2π radians. The 'official' answer of D is incorrect.
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
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.)

hidemi said:
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
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.

Steve4Physics said:
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!

## 1. What is Young's double-slit experiment?

Young's double-slit experiment is a famous experiment in physics that demonstrates the wave-like nature of light. It involves shining a beam of light through two narrow slits and observing the resulting interference pattern on a screen.

## 2. What are bright fringes in Young's double-slit experiment?

Bright fringes are the areas on the screen where the light waves from the two slits interfere constructively, resulting in a bright spot. These fringes occur when the path difference between the two waves is an integer multiple of the wavelength of light.

## 3. Why do bright fringes occur in Young's double-slit experiment?

Bright fringes occur because of the phenomenon of constructive interference, where two waves with the same frequency and amplitude overlap and combine to form a larger amplitude. In this case, the two waves are from the two slits and when they overlap on the screen, they create a bright fringe.

## 4. How can bright fringes be calculated in Young's double-slit experiment?

The position of bright fringes can be calculated using the equation d*sinθ = mλ, where d is the distance between the two slits, θ is the angle of diffraction, m is the order of the fringe (1, 2, 3, etc.), and λ is the wavelength of light. This equation is known as the diffraction grating equation.

## 5. What is the significance of bright fringes in Young's double-slit experiment?

The occurrence of bright fringes in Young's double-slit experiment is significant because it provides evidence for the wave nature of light. It also allows us to measure the wavelength of light and study the properties of interference and diffraction.

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