As we learned in the previous lesson, at the start of the 19th century, light was considered to be made up of particles or corpuscles. This view was strongly supported, swayed by the stature of Isaac Newton.
However, an experiment in the early part of the 19th century, provided a serious dent to this model.
In the early 1800s, Thomas Young decided to set up an experiment to verify the wave nature of light. This became Young's double slit experiment and provided compelling evidence of the wave nature of light.
This lesson reviews the behaviours of diffraction and interference and how this explains the behaviour of double slit diffraction, supporting a wave model of light.
It will also examine the mathematical models and we look at the use of diffraction grating, which allows for accurate analysis of light through interference patterns
However, an experiment in the early part of the 19th century, provided a serious dent to this model.
In the early 1800s, Thomas Young decided to set up an experiment to verify the wave nature of light. This became Young's double slit experiment and provided compelling evidence of the wave nature of light.
This lesson reviews the behaviours of diffraction and interference and how this explains the behaviour of double slit diffraction, supporting a wave model of light.
It will also examine the mathematical models and we look at the use of diffraction grating, which allows for accurate analysis of light through interference patterns
|
In a rush? Need a review? This video provide a quick summary of the double slit experiment. Otherwise, continue on... |
|
Young's Double Slit Experiment
|
|
Theory
This video examines the basis of this experiment including a mathematical analysis for the behaviour. |
Check your understanding
Interactive
Its now time for you to see the effect through this interactive (by Tom Walsh)
Its now time for you to see the effect through this interactive (by Tom Walsh)
This interactive allows you to see the conditions when constructive takes place.
The dots align exactly when this takes place
Alter any of the sliders and see the effect of the superposition of the two waves.
It is important to appreciate the mathematical formula of mλ = dsinθ , that only certain combinations of Y, d, L and λ will result in constructive interference.
You can do this by adjusting the various variables to generate constructive interference at the screen.
The dots align exactly when this takes place
Alter any of the sliders and see the effect of the superposition of the two waves.
It is important to appreciate the mathematical formula of mλ = dsinθ , that only certain combinations of Y, d, L and λ will result in constructive interference.
You can do this by adjusting the various variables to generate constructive interference at the screen.
Sample Problem
Below is a sample problem with a video that explain how to solve it. It is suggested you try the problem beforehand, as this actually aids understanding, even if you are unsure if you are correct.
Below is a sample problem with a video that explain how to solve it. It is suggested you try the problem beforehand, as this actually aids understanding, even if you are unsure if you are correct.
|
|
|
|
Diffraction GratingsInstead of using one, two or three slits to produce to diffraction and thus interference patterns (thereby demonstrating the way of nature of light), diffraction gratings are in essence many slits, like, well, a grating.
The result is much more defined diffraction patterns which increases the precision of the measurements. This video discusses the physics principles behind the diffraction with some examples. |
Interactive
We can now explore the formula mλ = dsinθ further. The animation lets you explore the effect of grating, wavelength and distance to the maxima separation. (by Tom Walsh)
A good way to use this is to
We can now explore the formula mλ = dsinθ further. The animation lets you explore the effect of grating, wavelength and distance to the maxima separation. (by Tom Walsh)
A good way to use this is to
- Set two variables yourself
- Measure the distance between the maxima
- Calculate the value for the remaining variable and compare it to the animation.
