This chapter covers the quantum phenomena of the photoelectric effect, excitation, fluorescence and line spectra. What is most important is to learn the ideas of photoelectric effect so you can construct a wordy answer to a 6-7 mark written question. Also make sure you know your Joules from your eV’s. Finally there are a lot of computer models to look at which help you visualise this topic make sure you spend the time looking through them
Planck's Constant - Experiment to Estimate the Value of Planck's Constant
In this video a range of seven LEDs are used to investigate the relationship between photon energy and frequency so that a value for Planck's constant can be estimated.
* Heads up: the value of Planck's constant obtained in this experiment is an estimate and as you will find my value is very different to the data book value. It's quite bad on one level, but on another it may be useful for evaluation! *
Experiments about quantum concepts, like this one, are mandatory practicals for many physics specifications. So this is good practice for OCR physics A, AQA A-Level physics, Edexcel A-Level physics, CPAC, PAG, practical endorsement.
Relevant concepts: Planck's constant, quantum physics, LEDs, photons, electrons and potential difference.[+] Show More
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Planck's Constant - Experiment to Estimate the Value of Planck's Constant
In this video a range of seven LEDs are used to investigate the [...]
In this video a range of seven LEDs are used to investigate the relationship between photon energy and frequency so that a value for Planck's constant can be estimated.
* Heads up: the value of Planck's constant obtained in this experiment is an estimate and as you will find my value is very different to the data book value. It's quite bad on one level, but on another it may be useful for evaluation! *
Experiments about quantum concepts, like this one, are mandatory practicals for many physics specifications. So this is good practice for OCR physics A, AQA A-Level physics, Edexcel A-Level physics, CPAC, PAG, practical endorsement.
Relevant concepts: Planck's constant, quantum physics, LEDs, photons, electrons and potential difference.[+] Show More
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Photoelectric Effect Demonstration
The Photoelectric effect helps to illustrate the wave-particle duality of [...]
A Scottish chemist called Joseph Swann tried passing electricity through fine wires (filaments) to make them glow white hot in 1860. Despite enclosing them in bulbs and pumping out the ...air, they quickly broke or blackened and Swann abandoned the idea. 17 years later, finding a better vacuum pump, he tried again. With no air left inside, the filament light bulb became a practical proposition.
Biology students: Subscribe to the Nucleus Biology ...channel to see new animations on biology and other science topics, plus short quizzes to ace your next exam: https://bit.ly/3lH1CzV
This medical animation depicts Laser Eye Surgery, a procedure that permanently changes the shape of the cornea, the clear covering over the front of the eye. #lasik #eye #cornea ANCE00185[+] Show More
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Fluorescent Lamps Explained with Quantum Physics - A Level Physics
This video introduces fluorescent lamps and explains them with quantum [...]
This video introduces fluorescent lamps and explains them with quantum physics for A Level Physics.
These common light fittings are used because they are relatively cheap and highly efficient. A glass ...tube is filled with mercury vapour at a low pressure. When excited by electrons the mercury atoms become ionised, losing an electron. As the electron returns to its ground state, it then emits an ultraviolet photon. A phosphor coating on the inside of the tube then absorbs the UV photon, finally emitting a range of visible photons which we see as white light.
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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How to demonstrate electron diffraction in the classroom
This demonstration shows that an electron beam is diffracted when it passes [...]
This demonstration shows that an electron beam is diffracted when it passes through graphite, showing electron wave behaviour and diffraction patterns.
The wave particle duality concept is central to understanding quantum [...]
The wave particle duality concept is central to understanding quantum physics. The A level specification introduces the DeBroglie equation and this experiment uses it along with the diffraction equation to ...find the spacing between carbon atoms in graphite.
A teacher must be present at all times during this experiment due to high voltages to the electron gun in the vacuum tube.
Phil Furneaux Ogden Science Officer Lancaster University 26th Jan 2017
Plasma Ball Excitation of a fluorescent lamp & CFL
A plasma globe or plasma lamp (also called plasma ball, dome, sphere, tube [...]
A plasma globe or plasma lamp (also called plasma ball, dome, sphere, tube or orb is a clear glass sphere filled with a mixture of various noble gases with a ...high-voltage electrode in the center of the sphere. Plasma filaments extend from the inner electrode to the outer glass insulator, giving the appearance of multiple constant beams of colored light
The plasma lamp was invented by Nikola Tesla after his experimentation with high-frequency currents in an evacuated glass tube for the purpose of studying high voltage phenomena
Although many variations exist, a plasma lamp is usually a clear glass sphere filled with a mixture of various gases (most commonly neon, sometimes with other noble gases such as argon, xenon and krypton) at nearly atmospheric pressure. They are driven by high-frequency alternating current energy at approximately 35 kHz, 2–5 kV. This energy comes from a lower-voltage DC power supply usually connected to mains power, and flows through a high-voltage transformer combined with a high-frequency electronic oscillator circuit which together output a high frequency and high voltage AC to the electrode).
We can use this one to allow electrons to flow into a low pressure mercury gas. The atoms become excited by collisions with electrons and an atomic electron is moved up an electron shell. We call this an “excited atom”. Sometime later the gas stops being excited as the electron falls back to its original shell emitting a photon of UV light. Then this photon of light is absorbed by the coating on the glass which has a similar process but this gives out a visible photon which you can see. This is a quantum effect and the bulb will only give out certain colours of light.[+] Show More
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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.[+] Show More
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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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Stimulated Emission Geissler Tubes
This is a simple experiment to show how colours of light can be split into [...]
This is a simple experiment to show how colours of light can be split into individual wavelengths of light using a simple diffraction tube.
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Stimulated Emission of Light
It's amazing how you can make the light move up the tube with a plasma ball!
It's amazing how you can make the light move up the tube with a plasma ball!
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Crookes Paddlewheel Tube
A Crookes Paddlewheel Tube (manufactured by Pressler!) The wheel is made [...]
A Crookes Paddlewheel Tube (manufactured by Pressler!) The wheel is made from mica (and has been painted with fluorescent paint). As I reverse polarity, the wheel changes direction.
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Maltese Cross Electron Wave Particle Duality Exp
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
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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Different excited states for different elements
Investigate exciting electrons by collisions – many atoms
