This page covers the relativity section of the course.
The key to understanding the Michelson–Morley experiment (Topic 3.1) is realising that turning the apparatus through 90º alters the relationship between the beam paths and the Earth’s motion – no matter which way the Earth is moving. The null result disproves the ether theory.
Inertial frames of reference can be explained as places where the observer is considered to be at rest compared to the measuring equipment they are using. Since the value of the speed of light is always the same, then the observer’s measuring equipment (their ruler or their clock) must adapt to conform with any relative motion. Thus at high relative velocities their ruler would shrink and their clock would slow so as to indicate the correct readings.
Did you know that everything is moving? Even you, as you're sitting perfectly still, because the earth is moving, and the sun, and the galaxy, and so forth. For this ...reason, it only makes sense to talk about the motion of some object relative to some other object, just as Galileo told us. Watch this and see what I mean!
Did you know that everything is moving? Even you, as you're sitting ...
Did you know that everything is moving? Even you, as you're sitting perfectly still, because the earth is moving, and the sun, and the galaxy, and so forth. For this ...reason, it only makes sense to talk about the motion of some object relative to some other object, just as Galileo told us. Watch this and see what I mean!
This physics video tutorial provides a basic introduction into relative ...
This physics video tutorial provides a basic introduction into relative velocity problems in one dimension. It explains the concept of the frame of reference and how it's used to ...determine the relative velocity of an object with another regardless if the two items are traveling in the same direction or in the opposite direction. This video contains a few examples of car and train problems traveling in the same direction and in the opposite direction toward each other. It provides all of the formulas and equations needed to calculate the relative velocity.
The experiment which tried to prove the existence of a mysterious medium for light called ether but failed at it. It instead proved that light ...does not need a medium to travel.
Background Music: Interstellar Sitar [http://freemusicarchive.org/music/Dana_Boule/We_All_Need_To_Calm_Down/Interstellar_Sitar_1847][+] Show More
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Einstein's twin paradox explained - Amber Stuver
Follow two astronauts into outer space to explore time dilation and ...
Follow two astronauts into outer space to explore time dilation and Einstein’s theory of relativity through the Twin Paradox thought experiment.
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On their 20th birthday, identical twin astronauts volunteer for ...an experiment. Terra will remain on Earth, while Stella will board a spaceship. Stella’s ship will travel to visit a star that is 10 light-years away, then return to Earth. As they prepare to part ways, the twins wonder what will happen when they’re reunited. Who will be older? Amber Stuver investigates the “Twin Paradox.”
Lesson by Amber Stuver, directed by Aim Creative Studios.
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Relativistic Mass and Energy
Does Relativistic Mass actually exist?
Does Relativistic Mass actually exist?
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Time Dilation - Einstein's Theory Of Relativity Explained!
Time dilation and Einstein’s theory of relativity go hand in hand. Albert ...
Time dilation and Einstein’s theory of relativity go hand in hand. Albert Einstein is the most popular physicist, as he formulated the theory of relativity, which gave the Energy mass ...equivalence formula and is directly related to time dilation. But what is time dilation? Time dilation and space time are interrelated. Einstein made one of the most important contributions to physics and had the concept of space time explained. A simple explanation of space time is that it is a mathematical model that fuses the three dimensions of space and the one dimension of time into a single four-dimensional continuum. But it is very important to understand that the general theory of relativity and the special theory of relativity are different. In this short animated video, we give a simple explanation of time dilation and Einstein’s theory of relativity and also explain how time slows down in a moving vehicle!
Thanks to Brilliant.org for supporting MinutePhysics! The first 200 people ...
Thanks to Brilliant.org for supporting MinutePhysics! The first 200 people who go to http://www.brilliant.org/minutephysics will get 20% off a Premium Subscription to Brilliant.
This video is about how terrestrial muons ...are part of our experimental proof of time dilation, length contraction, and special relativity in general.
This page covers the wave particle duality section of the course.
One way of modelling Newton’s corpuscular theory of light (Topic 2.1) is a rough demonstration of refraction using a ball rolling down a slope. Fold and support a large piece of card so that there are two flat surfaces separated by a short broad ramp. If a small ball is made to roll obliquely down the ramp from the higher surface to the lower, its direction changes (towards the normal) as it speeds up. The students can investigate Young’s fringes with either light or 3 cm microwaves, depending on the equipment you have available. An appropriate risk assessment should be carried out, especially if you are using a laser for the light source. You may be surprised to learn that Newton maintained his support for the corpuscular theory despite having studied Newton’s rings – which provide strong evidence in favour of the wave nature of light.
Electromagnetic waves (Topic 2.2) can be demonstrated using 3 cm microwaves. Most microwave kits include the extra equipment needed to demonstrate and investigate the properties of waves. For instance, students should be able to measure the wavelength by setting up a standing wave with an aluminium reflector and using the probe to locate the maxima and minima. Other wave properties that can be studied using 3 cm microwaves include diffraction and polarisation.
We can introduce wave–particle duality via the photoelectric effect (Topic 2.3), which shows why a particle theory of light won favour again. Students should understand the difference between photons and photoelectrons. Simply put, it is the photons that go in and photoelectrons that come out. The idea of a minimum energy may be hard to grasp, but a simple analogy for the photoelectric effect is for students to think of a sculptor chipping away at a stone block. Insufficient energy produces no result; a hard blow chips a little away; a harder blow can send a small chip flying. If you calculate some photon energies for different types of electromagnetic waves (using E = hf or E = hc/λ) they can relate this energy to the position in the electromagnetic spectrum, which they should recall from their GCSE work.
A simple way for understand how to measure the Planck constant is by using LEDs of different colours. Students should measure the forward bias voltage (V) that just switches each LED on. Manufacturers supply values for the wavelength (λ) of the light produced by their LEDs. Once students are clear that in this case the energy flow runs the other way from that in the photoelectric effect, they can substitute their values in eV = hc/λ.
The discovery of electron diffraction (Topic 2.4) substantiated de Broglie’s hypothesis. It is a useful exercise to calculate the de Broglie wavelength for various particles – for instance electrons moving in a TV tube or protons in an accelerator beam.
This chapter can be difficult. The concept of wave–particle duality involves new concepts. You should try to develop confidence with the formulae and calculations used to test understanding of this material in examinations.
This simple idea shows how energy is not conducted well by a fluid. Heat ice and water to see if boil at the top and and still be frozen at ...the bottom.[+] Show More
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Liquids Conduct Heat Poorly
This simple idea shows how energy is not conducted well by a fluid. Heat ...
This simple idea shows how energy is not conducted well by a fluid. Heat ice and water to see if boil at the top and and still be frozen at ...the bottom.[+] Show More
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Maltese Cross Electron Wave Particle Duality Exp - AQA A Level Physics
The electron gun fires a beam of electrons that spread out as they travel ...
The electron gun fires a beam of electrons that spread out as they travel across through the vacuum towards the screen. In the path of the beam there is a ...metal cross. The electrons that hit the cross are stopped by the metal, but those that get past it hit a fluorescent screen at the far side of the tube which glows green when the electrons collide with it.
A sharp silhouette of the cross can be seen on the screen and this shows that the electrons travel in straight lines.
The anode voltage is a few thousand volts and the same voltage is also connected to the Maltese cross. If this voltage is increased the electrons gain more energy and so are moving faster when they hit the screen. This makes it glow more brightly. Turning up the heater voltage also makes the screen brighter because the electron gun is producing more electrons due to the hotter heater.
If you touch the front of the screen the silhouette will move because you are earthing it. Electrons that had collected on the glass flow through you to the ground.
Holding a magnet near the tube (especially near the electron gun or near the silhouette of the cross) will distort the picture showing that electron beams are affected by magnetic fields. Think about where the poles appear?
The Cloverleaf is when you take out the positive connection to the cross and the electrons build up on the cross and repel the electrons which are accelerated away[+] Show More
How does the electron gun work? Thermionic Emission and Particle Acceleration - A Level Physics
What's the speed of an electron accelerated through 5000V? An electron gun ...
What's the speed of an electron accelerated through 5000V? An electron gun works by thermionic emission and particle acceleration. The Electron gun is essentially a linear accelerator. ...In this video I[+] Show More
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Episode 23 Electrons
Amazing Eureka Physics video series from 1 to 30 which through cartoon go ...
Amazing Eureka Physics video series from 1 to 30 which through cartoon go through the amazing world of KS3 to A-Level Physics teaching with key concepts.
First released in Canada but ...still going strong![+] Show More
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Maltese Cross Electron Wave Particle Duality Exp - AQA A Level Physics
The electron gun fires a beam of electrons that spread out as they travel ...
The electron gun fires a beam of electrons that spread out as they travel across through the vacuum towards the screen. In the path of the beam there is a ...metal cross. The electrons that hit the cross are stopped by the metal, but those that get past it hit a fluorescent screen at the far side of the tube which glows green when the electrons collide with it.
A sharp silhouette of the cross can be seen on the screen and this shows that the electrons travel in straight lines.
The anode voltage is a few thousand volts and the same voltage is also connected to the Maltese cross. If this voltage is increased the electrons gain more energy and so are moving faster when they hit the screen. This makes it glow more brightly. Turning up the heater voltage also makes the screen brighter because the electron gun is producing more electrons due to the hotter heater.
If you touch the front of the screen the silhouette will move because you are earthing it. Electrons that had collected on the glass flow through you to the ground.
Holding a magnet near the tube (especially near the electron gun or near the silhouette of the cross) will distort the picture showing that electron beams are affected by magnetic fields. Think about where the poles appear?
The Cloverleaf is when you take out the positive connection to the cross and the electrons build up on the cross and repel the electrons which are accelerated away[+] Show More
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Electron Diffraction De Broglie Waves and Nucleus Diameter - AQA A Level Physics
Electron diffraction refers to the wave nature of electrons. However, from ...
Electron diffraction refers to the wave nature of electrons. However, from a technical or practical point of view, it may be regarded as a technique used to study matter by ...firing electrons at a sample and observing the resulting interference pattern.
Electron diffraction is the phenomenon resulting from the interaction between electrons and crystalline materials, producing a pattern of rings or spots that characterize the sample (Glauber and Schomaker, 1953). The De Broglie wavelength is similar to the atomic spacing.
This phenomenon occurs due to the wave-particle duality, which states that a particle of matter (in this case the incident electron) has wave properties as well as particle properties.[+] Show More
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Circular Electron Beam in Magnetic Field
This is how you can work out e/m for circular beam of electrons thermionic ...
This is how you can work out e/m for circular beam of electrons thermionic emitted from a filament.
It uses both electric fields and mag fields and Helmholtz coils.
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Perrin Tube - Electron Demo A2 AQA Mag Fields Discovery of the Electron and Charge
The stream of electrons or "cathode rays" are deflected into a Faraday ...
The stream of electrons or "cathode rays" are deflected into a Faraday cage, which is connected to an electroscope, to show that electrons have a negative charge.
It is important ...that the whole beam should enter the cylinder to avoid the production of secondary electrons by the beam striking the sides. For this reason it is more reliable to use the coils to deflect the beam than to do the experiment with a bar magnet deflecting the beam as I have done here.
You may find that the charge leaks away as soon as you remove the magnetic field that is causing the deflection. So it is best to view the effects live.
Result is to prove that cathode rays have a charge, which you can then go on to show is negative. Also that they have mass and obey the formulas used in A2 Physic for a particle moving in a B-field
