# Single Slit Interference Pattern: Increased Distance

• belbin09
In summary, when the screen is moved further away, the effect on the pattern would be wider bright fringes, decreased light intensity of the bright fringes, and the bright fringes appearing closer together. This is due to the spreading of light as the distance between the slit and screen increases. It is unclear whether the dark fringes would actually get smaller or if it is just a perception. To answer this, one must consider relevant expressions and quantities related to the appearance of bright and dark fringes.

#### belbin09

Homework Statement
A laser emitting light with a wavelength of 560 nm is directed at a single slit, producing an interference pattern on a screen that is 3.0 m away. The central maximum is 5.0 cm wide.

What would the effect on this pattern be, if the screen was moved further away?
Relevant Equations
Δy = λL/w
ATTEMPT AT SOLUTION

The effect on the pattern when the screen is moved further away is the bright fringes would become wider, the light intensity of the bright fringes would decrease, and the bright fringes will appear closer together.

REASONING

I answered this question based on how light works against a screen in general. The part I get stuck on is how the dark fringes would appear. I state that the bright fringes "appear" closer together because as the distance between the slit and the screen increases the bright fringes would become wider, spreading the light outwards making the dark fringes harder to distinguish. Would the dark fringes actually get smaller or is it just a perception?

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What expressions do you know about where the bright and dark fringes appear? What quantities are relevant? Start from there.