# Calculating Fringe Positions in Two-Slit Interference Patterns

• Barry Melby
In summary, the conversation is about determining the distance of the third-order bright fringe from the central bright fringe in a two-slit grating pattern. The fifth-order dark fringe is given to be 45.0 mm away from the central bright fringe, and the question is how to find the third-order bright fringe without knowing the wavelength or slit width. The suggested approach is to refer to a textbook or section on two slit interference and use the equations provided there.
Barry Melby

## Homework Statement

[/B]
Light passing through a two-slit grating makes a pattern on a screen located 500 mm away. In this pattern, the fifth-order dark fringe is 45.0 mm from the central bright fringe. How far from the central bright fringe is the third-order bright fringe?

## Homework Equations

This is what I'm looking for help on.

## The Attempt at a Solution

I'm not even sure which equations to use to solve this. Any ideas?

You got a textbook you are working with? Is there a section on two slit interference (aka Young's double slit experiment)? What equation does it give there?

it's not in my book. any ideas?
How do i go about this with a dark fringe and a bright fringe if i don't know the wavelength or slit width?GOT IT.

Last edited:

## What are dark and bright fringes?

Dark and bright fringes refer to the alternating areas of light and dark bands that appear in patterns of light interference, such as in the double-slit experiment.

## What causes dark and bright fringes?

Dark and bright fringes are caused by the interference of light waves. When two or more waves overlap, they either amplify or cancel each other out, resulting in areas of high and low intensity.

## How can dark and bright fringes be observed?

Dark and bright fringes can be observed by passing light through a slit or small opening, which acts as a source of coherent waves. These waves then interfere with each other, forming the characteristic fringes.

## What is the significance of dark and bright fringes in science?

Dark and bright fringes are important in understanding the wave nature of light and the principles of interference. They have also been used in experiments to study the properties of light and to make precise measurements.

## Can dark and bright fringes be seen in other types of waves?

Yes, dark and bright fringes can also be observed in other types of waves, such as sound waves and water waves. This phenomenon is known as wave interference and follows the same principles as in light interference.

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