# Young's double slit experiment

• Crystal037
In summary: What's a "parallel" beam of light?Parallel to each other I am talking about parallel beams of light that pass through both the slit.
Crystal037
Homework Statement
Why parallel beam of light is used for ydse?
Relevant Equations
I(resultant) = I1+I2+rt(I1*I2cosx)
Where x is the phase difference
I know that ydse is based on interference of light when it passes through an obstacle having almost same aperture as the wavelength of light. Also they should be coherent to have a constant phase difference at every point. But I don't get why the light beams should be parallel?

Crystal037 said:
Homework Statement:: Why parallel beam of light is used for ydse?
Homework Equations:: I(resultant) = I1+I2+rt(I1*I2cosx)
Where x is the phase difference

I know that ydse is based on interference of light when it passes through an obstacle having almost same aperture as the wavelength of light. Also they should be coherent to have a constant phase difference at every point. But I don't get why the light beams should be parallel?

Do you mean why are the slits are aligned perpendicular to the wavefront? If not, then what do you suggest?

No I mean why we take parallel beam of light i.e. Why do take the light source at the focus of convex lens and then that light is passed through the slit. What if we don't use the parallel light beams.

Crystal037 said:
No I mean why we take parallel beam of light i.e. Why do take the light source at the focus of convex lens and then that light is passed through the slit. What if we don't use the parallel light beams.

What's a "parallel" beam of light? Parallel to what?

The beam has to be focused at the slits. If not, it misses the slits and you don't have an experiment.

Parallel to each other I am talking about parallel beams of light that pass through both the slit

Crystal037 said:
Parallel to each other I am talking about parallel beams of light that pass through both the slit
If you have two beams of light that are not parallel to each other, then where are they coming from and what are they aimed at?

If you are proposing an alternative set-up why don't you describe it?

Basically you want plane waves for a simple setup (what you call parallel beam) in order to have the simplest mathematical description.

but the interference will also occur for a screen at an angle, a spherical wavefront coming from the left, etc.
Best thing to do (if you have a chance ) is to do the experiment and play with the setup !

PeroK
Crystal037 said:
Parallel to each other I am talking about parallel beams of light that pass through both the slit
If you have non-parallel beams, you will need for the light to have a phase relationship. Two flashlights, each pointed at one of two slits will not have a phase relationship.

An arrangement with half-silvered mirrors and two different convergent paths could do the trick. (Aka holography).

## What is Young's double slit experiment?

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

## Why is the interference pattern created in Young's double slit experiment?

The interference pattern is created because light behaves as a wave, and when the light from two slits overlaps, it creates regions of constructive and destructive interference, resulting in the bright and dark fringes on the screen.

## What is the significance of Young's double slit experiment?

The significance of this experiment is that it provided evidence for the wave theory of light and helped to establish the field of optics. It also paved the way for further research and understanding of the wave-like properties of particles, known as wave-particle duality.

## How does changing the distance between the slits affect the interference pattern in Young's double slit experiment?

Changing the distance between the slits alters the path length difference between the two beams of light, resulting in changes to the interference pattern. A smaller distance between the slits leads to a wider interference pattern, while a larger distance results in a narrower interference pattern.

## Can the Young's double slit experiment be performed with other types of waves besides light?

Yes, this experiment can be performed with any type of wave, such as sound waves or water waves. The only difference is that instead of a screen, the interference pattern will be observed on a detector that can measure the intensity of the wave at different points.

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