This section has some quite tricky concepts and really you need to look at the animations and play with the settings to get a feel for what happens to x when I change y etc.. You also need to learn the key diagrams as this will help your explanations. Finally look carefully at the derivations as they also will help you explain the tricky stuff.
Amazing Refraction Magic Trick - The Appearing Beaker
Works on refraction and refractive index being matched.
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Amazing Refraction Magic Trick - The Appearing Beaker
Works on refraction and refractive index being matched.
Works on refraction and refractive index being matched.
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Laser Refraction of Light
This demo shows how you refract light by passing into a denser medium i.e. [...]
This demo shows how you refract light by passing into a denser medium i.e. water. The light slows down so as c is lower than the speed of light the ...wavelength changes (reduces) and it interacts with the medium differently.
Refraction = slowing or speeding up of waves in another medium.
Change of angle can happen when the light enters at an angle which is not at 90 degrees to the normal.
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Refraction and Reflection of Laser Light
This is a simple video to show the principle of the refraction of light and [...]
This is a simple video to show the principle of the refraction of light and also the reflection of light using laser monochromatic light. You can clearly see that the ...light changes direction inside the prism or slows down. This is the idea of "refraction". It turns in towards the normal then away as it exits. The pathway is a constant refraction as the density is even throughout. This is not always the case for example in water the pressure changes cause curved refraction, as it the same effect with seismic waves travelling through the Earth. Interesting as well to see something which students often miss as the reflected ray on the surface of the block or the TIR or totally internally reflected rays from the internal surface of the prism.
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Reflection and Refraction
This movie shows refraction, reflection, TIR with prisms.
This movie shows refraction, reflection, TIR with prisms.
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Dispersion of Laser light
Amazing fun, with lasers
Amazing fun, with lasers
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Neon Spectral Images AS AQA Physics
Spectral lines shown on a spectroscope from a neon geissler tube. This is a [...]
Spectral lines shown on a spectroscope from a neon geissler tube. This is a great quantum effect!
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Spectral Absorption (for A-Level Physics)
When the energy gap between two molecular energy levels is exactly the same [...]
When the energy gap between two molecular energy levels is exactly the same as the photon energy of an incident beam of light, some of the incident light will be ...removed from the beam. On the single-molecule level, the energy of an absorbed photon drives an absorption transition, a nearly instantaneous process that causes the molecule to jump from its ground state to an excited state. Accordingly, the intensity of the light that is transmitted through a solution can be used to determine how many molecules are present in the solution per unit volume.
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Refraction of Light - Introduction | Don't Memorise
What is Refraction of Light? Is Reflection of Light different from [...]
What is Refraction of Light? Is Reflection of Light different from Refraction of Light? Watch this video to know more!
Total Internal Reflection and Critical Angle - A Level Physics
This video introduces and explains total internal reflection and its [...]
This video introduces and explains total internal reflection and its relationship with the critical angle for A Level Physics.
Total internal reflection occurs when light reflects off of the boundary between ...two mediums. Where light gets refracted such that the angle of refraction is greater than the angle of incidence, at some angle, the light will be refracted at an angle of 90 degrees and is reflected instead. The smallest angle of incidence that this occurs at is called the critical angle.
Thanks for watching,
Lewis
This video is recommended for anyone studying A Level Physics in the following exam boards: AQA CIE Edexcel Edexcel IAL Eduqas IB OCR A OCR B WJEC
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This video explains how optical fibres (or optical fibers if you're [...]
This video explains how optical fibres (or optical fibers if you're American) work for A Level Physics.
Optical fibres use total internal reflection in order to send information. A light signal ...is sent down an optical fibre which can be received quite a distance away. The signal isn't perfect because different light rays travel different distances - this is called modal dispersion. The signal is put through a filter in order to get the original signal back out.
Thanks for watching,
Lewis
This video is recommended for anyone studying A Level Physics in the following exam boards: AQA CIE Edexcel (don't need to know details) Edexcel IAL Eduqas IB OCR A OCR B WJEC
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This video introduces and explains Young's double slit experiment for A [...]
This video introduces and explains Young's double slit experiment for A Level Physics.
Everyone loves lasers in Physics. Young's double slit experiment uses the constructive interference and destructive interference of light ...from a laser to calculate and measure the wavelength of light. We need the separation of the slits, distance to the screen and separation of the light and dark fringes. You can do this practical without a laser as well.
Thanks for watching,
Lewis
This video is recommended for anyone studying A Level Physics in the following exam boards: AQA CIE Edexcel Edexcel IAL Eduqas IB OCR A OCR B WJEC
_____________________________________
MY PHYSICS WEBSITES Find even more videos organised by exam board and topic at:
MY YOUTUBE CHANNEL Your support in watching this video has been invaluable! To contribute towards the free videos on YouTube, make a small donation at: ► https://www.paypal.me/physicsonline
The double-slit experiment is a classic experiment that is frequently [...]
The double-slit experiment is a classic experiment that is frequently referred to when describing quantum phenomena, so we definitely have to go over it a little bit. What happens when ...you pass a beam of light through a screen with two slits? What about when you send electrons through there? Or just one electron? It's crazy stuff! Check it out.
Quantum physics is the study of the interaction of atoms and the microscopic universe. Quantum Physics gave us TV ...(the image is formed by electrons being shot at a layer of phosphorous on the inside of the screen.) Quantum also gave us microwave ovens, lasers, cell phones, nuclear energy, and the atom bomb.
In the early days Quantum researchers did various experiments on electrons, or the tiny particles that seem to fly around the nucleus of an atom and of which everything in our present existence is made. The results of these experiments caused the world of physics to question many of its laws, and even had Einstein losing it over what it all meant. Neils Bohr, Wolfgang Pauli, Werner Heisenberg, John Bell, and Erwin Schrodinger who made achievements in Quantum physics were all given Nobel Prizes. Unless Nobel Prizes are given for myths or to idiots, the experiments listed below are definitely worth our contemplation.
a) The most important experiment was known as the Double Slit Experiment.
This experiment was simply done; if you take a gun and shoot black sand, through 2 slits on a metal plate with a white wall behind it you will get an image that looks like this on the white wall:
I I
If you point a flashlight through the 2 slits you will get an image on the wall that looks like this:
I I I I I I I I
This is called an interference pattern and you may notice how the lines in the middle are stronger than the ones on the edges as is common in all experiments done with light waves - water ripples are similar to light waves. Everything in our present existence is made of either matter (solid particles) or light.
This experiment is a basic yet very effective method of differentiating between waves and what is composed of particles -- or matter - on the atomic level.
Back to electrons: when scientists shot electrons through the plate with the double slit the result was that of a wave
I I I I I I I I
This drove the scientific community nuts as they thought that electrons were particles made of matter. After much controversy, theories as to why, and repeated experiments scientists decided to watch exactly what the electrons were doing as they passed through the 2 slits. The result that followed turned the world of physics around. When the electrons were observed the result was:
I I matter
When the observation device was switched off the result was again:
I I I I I I I I a wave
Electrons would switch from waves into matter particles instantly and only when scientists were observing them. Did the electrons seem to know somehow when they were being watched and would snap into being particles of matter and "behave" only when they were being observed? For anything on the planet to be switching back and forth from waves into matter is impossible. - It does not compute. This phenomenon is now called in Quantum "The Collapse of a Wave."
The Collapse of a Wave has been one of the most startling discoveries of Quantum Physics. Physicists have a stream of theories, but this simple yet unexplainable experiment declared to humanity that everything we are looking at-- as completely irrational as it may seem - on the quantum level - turns into reality or solid form - only when it is observed. No one really knows what is going on down there; there is no real explanation possible. Without the observer - nothing is solid.
Einstein grew increasingly troubled by the "Collapse of a Wave" and toward the end of his life at one point during a heart-to-heart talk with physicist Abraham Pais asked "Do you really believe the moon exists only when I look at it?" Does everything only exist when it is being observed? This would mean consciousness is creating what we see with our eyes. Many theories have been given in regards to the Collapse of a Wave; the most popular being co-dimensions existing at the same time and electrons are switching back and forth between them.
Another is the existence of a sort of "fabric" that connects everything in the universe. When consciousness "observes" the fabric then the solid image forms ...
Presently all quantum physics equations now have the "observer" factor added. Stephen Hawkings recently said that whoever can decipher Quantum has deciphered the language of the universe.
I give a derivation of Young's double slit formula. The double slit formula is used to find the pattern ...that the interference of two light waves create when they pass through double slits in a diffraction grating.
Young's double slit formula connects the distance between two slits in a diffraction grating, the distance from the diffraction grating to the wall, the distance between points of maximum constructive interference, and the wavelength of light.
0:00 What the Equation is Predicting 1:33 Path Difference, and Constructive and Destructive Interference 5:26 Drawings of Double Slit Experiments are Exaggerated 5:40 The Visual Pattern of Constructive and Destructive Interference 6:01 Proving the Equation
Now that we have proved Young's Double Slit Interference Equation, we can [...]
Now that we have proved Young's Double Slit Interference Equation, we can use it to solve for missing variables in the double slit experiment like the length between maxima, distance ...between the wall and the diffraction grating, the distance between the double slits, and the wavelength of the light.
Diffraction Gratings in a Snap! Unlock the full A-level Physics course at [...]
Diffraction Gratings in a Snap!
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Measuring Wavelength of Light with a Diffraction Grating - PRACTICAL - A Level Physics
In this video I go through an AQA Physics A Level Required Practical that [...]
In this video I go through an AQA Physics A Level Required Practical that uses a diffraction grating experiment to investigate the properties and to measure the wavelength of light. ...(This is AQA Required Practical 2.) This is also the OCR A Level Physics PAG 5.1 Practical.
A laser will diffract and interfere when shone through a diffraction grating. The distance to the first, second and third order maxima can be measured which will then allow the wavelength of the light to be calculated. Be careful with the laser. Do not look at the beam or any reflected light from a shiny surface.
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