Quanta & Waves Resources

Resources: Notes and video (flash learning AH CfE Virtual Physics)

Read the notes, watch the video and answer the questions below, in a way that makes them form a good note about the subject.

  1. What three pieces of key evidence didn’t fit with classical physics?
  2. In 1911 Rutherford put forward his model of the atom, a) State the important features of this model b) What provides the centripetal force for the electrons in this model?
  3. Describe black body radiation.
  4. State two changes with the black body radiation curve as temperature increases.
  5. Describe the UV catastrophe.
  6. Who helped solve the UV catastrophe and in what ways?
  7. Which piece of the photoelectric effect experiment demonstrates that energy is not transferred as waves?
  8. From the photoelectric effect state the link between the energy of the photon and a) the frequency of the radiation, b) the wavelength
  9. What did Bohr postulate about angular momentum?
  10. State the formula for angular momentum in Bohr’s model of the atom, (define each term)
  11. State the limits for the Bohr model of the atom
  12. Explain the observation made by GP Thomson in 1920 which led to further debate on the issue.
  13. What did de Broglie imply was the link between electrons as waves and particles?
  14. Explain the confusion caused when looking at the double slit experiment with single particles.
  15. What happens when you observe an electron passing through the slit?
  16. What two quantities cannot be measured together with much certainty and why?
John Sharkey’s Virtual Physics CfE AH Particles from Space
John Sharkey’ SHMs Virtual Physics CfE AH
John Sharkey’s Waves Virtual Physics CfE AH
This is additional support for travelling waves

Here is a nice little video on Standing Waves. Standing waves are formed when a wave interferes with its reflection to produce nodes and antinodes.

…..and here is the explanation for the standing wave video

John Sharkey’s Interference Virtual Physics CfE AH
John Sharkey’s CfE AH Polarisation

Resources

Below are some accumulated resources. Thanks to all of those who produced them.

ah-quanta-summary notes problems-2015 Thanks to RGC for these notes

quanta-and-waves-student-booklet-i-ror Thanks to Mr Orr for these.

Quanta and Waves Student booklet I ROR pdf version of the above

4.2 Energy changes during simple harmonic motion

ah waves summary notes and problems 2013 RGC notes thanks for these

PhysicsQuantaandWaves_tcm4-726389 Andrew McGuigan Numerical Questions

ah quanta summary notes and problems 2015 LA

ah quanta tutorial solutions 2015

ah uncertainties experiments 2013

ah waves summary notes and problems 2013

ah waves tutorial solutions 2013

Quanta

glossary-of-terms-table2

stellar  physics pdf       stellar physics.doc

Properties_of_stars_and_stellar_evolution

electrons-exhibit-both-wave

cosmic-rays A quick research task on cosmic rays.

cosmic-rays-answers The answers to the sheet above.

solar-wind-magnetosphere

solar-wind-magnetosphere-answers

Scientist think that the Earth is due a “Magnetic Flip” Research this starting at the link below and then answer the AH Revised question on this from the 2015 Paper Q11

Here is a Radio 4 programme talking about the consequences of a polar flip. If you want to view further programmes click on the link below.

http://www.bbc.co.uk/curious case of Rutherford and Fry

https://www.physics.org/facts/frog-magnetic-field.asp

soho_fact_sheet

The number of sunspots is an indication of solar activity. Research this and then complete the AH Revised 2013 paper Q6.

quantum-mechanics

unit-2-part-1-quanta-notes

Quantum Tunnelling – strange but true

Background

What is the Uncertainty Principle? Minute Physics

Quantum Tunnelling is the process by which a particle gets across a barrier that it cannot classically pass.

It is related to wave-particle duality in that it is a result of the wave nature of a particle.

The probability of the particles getting through the barrier drops exponentially with the thickness of the barrier.

“>What is Quantum Tunnelling? Minute Physics

How to walk through walls- Quantum Tunnelling

Is Quantum Tunnelling faster than the speed of light?

Quantum Entanglement

 

 

Waves

shm-intro

unit-2-part-2-waves-notes

shm INTRO

PhysicsQuantaandWaves_tcm4-726389

Tutorial AH Revised Booklet v2

AH (SHM)

Signature

December 2020


SHM Practicals

The AH today were working in 3 groups to research via practicals and notes about SHM. The task is given below. Well done to Morford and Hodgson who created the following from their practical, with very little assistance. Their results were so good I thought I’d share them.

Mr Morford wrote
“These graphs are from our recent experiment to determine the effect of damping on an oscillating mass. A mass was hung from a spring over an Alba Ranger ultrasound device. We then analysed our measurements using excel and graphed our results to find the decay due to damping.”

Morford & Hodgson (2019)
Check out the great phase lag and the obvious proof of SHM showing a is proportional to -ky
The period isn’t constant because the spring started moving with horizontal motion but the amplitude certainly deteriorated
I’ll need to check this….but it looks good!

This was the task for the class and my thanks to the IoP for their Practical Physics lessons and to the other places referenced for some great practical techniques. I will neaten this post later, but I promised Morford and Hodgson that I would post tonight!

Hopefully I can collate the rest of the groups information soon.

By the end of the lesson you should……

  • You to have the spring constant for two of the springs by two different methods.
  • A graph of d against t, v against t, and a against t
  • A value of the period of spring for various masses
  • Discovered the effect of amplitude on the period Found the effect of damping (so find out what that is)

https://www.webassign.net/question_assets/ncsucalcphysmechl3/lab_7_1/manual.html

https://www.birmingham.ac.uk/undergraduate/preparing-for-university/stem/Physics/stem-legacy-SHM.aspx

https://www.cyberphysics.co.uk/topics/shm/springs.htm

http://practicalphysics.org/investigating-mass-spring-oscillator.html

2020

Despite Covid-19 the intrepid AH students have been showing damping with a pendulum bob and tracker. The original movie has still to be analysed by our friends from Annan

This is Courault and Douglas with bob skimming the water and you can see some damping on the graph. Note the period remains constant but the amplitude, and hence energy is reduced. Well done Courault and Douglas, imortalised in your tracker movie!
This is Patterson and Pritchards attempt with bob fully immersed as it goes through its swing. You can see bob is far more damped! I think Pritchard was a little lazy with his identification of the edge of bob as that period is definitely changing! Compare this damping with the previous one. Well done to both of you!

Now if we can add Atwal, Burns, Carson and Morrin’s tracker we can have a full set for 2020 and you can look back with fondness at your time in AH, despite all the distancing.

Investigating a mass-on-spring oscillator

Demonstration

A mass suspended on a spring will oscillate after being displaced. The period of oscillation is affected by the amount of mass and the stiffness of the spring. This experiment allows the period, displacement, velocity and acceleration to be investigated by datalogging the output from a motion sensor. It is an example of simple harmonic motion.


Analysis 
Measurement of period 
Period and Amplitude Observe that the period appears to be independent of amplitude. 
 
Effect of mass 
A straight line is the usual result, showing that the period squared is proportional to the mass. 
 
Velocity and acceleration 
A plot of the resulting data shows a ‘velocity vs. time’ graph. Note that the new graph is also sinusoidal. However, compared with the ‘distance vs. time’ graph, there is a phase difference – the velocity is a maximum when the displacement is zero, and vice versa. 
 
A similar gradient calculation based on the ‘velocity vs. time’ graph yields an ‘acceleration vs. time’ graph. Comparing this with the original ‘distance vs. time’ graph shows a phase difference of 180°. This indicates that the acceleration is always opposite in direction to the displacement. Teaching notes

Aim: To find the force constant of a helical spring by plotting a graph between load and extension.

Aim: To find the effect of damping on an oscillating spring

Aim: To find the effect of mass on an oscillating spring

Aim: To use the formula for an oscillating spring to find m or k etc

Signature
December 2020

Damping Practicals

Using Tracker to Discuss Damping

Great teamwork this week, with teachers, technicians and students all getting some great results using tracker.

We wanted to see if we could get some damping examples.

We took a pendulum that was just over a metre long and set it in motion over a blue tray. We filmed the pendulum and uploaded this into tracker. Part of a metre stick was used for calibration purposes.

Theo has analysed this to try to show that the amplitude remains constant, if there is no damping. The graph does seem to shift a little towards the positive direction and we are having some good ideas as to why, such as camera slide and swinging forward and back rather than side to side,  but it was probably due to the blurred film.

We then poured water into the tray and repeated the experiment pulling the pendulum back to the same point. Angus produced the tracker trace below. This is pretty blurred and distorted due to the refraction by the water.

Daniel had a clearer film to analyse and got a great plot of displacement with time to show how the amplitude decays with time.

If you can afford the top of the range camera, unlike the teacher, you can get a lovely plot, even if the pendulum appears to be hanging upside down!

You can clearly see that the amplitude decreases. Calculating the period, peaks arrive at the following times

Time (s)
2.23
4.67
7.07
9.53
11.9
14.4
16.8
19.3

This gives a period of approx. 2.4-2.5 seconds.

Quantum Mechanics

  • I think I can safely say that nobody understands quantum mechanics.

But here is a great video to help you understand what is happening

Quantum Theory Full Documentary

https://youtu.be/CBrsWPCp_rs?t=207 this link is set up so you miss the blurb at the beginning.

Here is a link to brief notes on the important discoveries leading to the Quantum Mechanics ideas we know today.

The Sectrets of Quantum Physics

  • We have always had a great deal of difficulty understanding the world view that quantum mechanics represents. At least I do, because I’m an old enough man that I haven’t got to the point that this stuff is obvious to me. Okay, I still get nervous with it…. You know how it always is, every new idea, it takes a generation or two until it becomes obvious that there’s no real problem. I cannot define the real problem, therefore I suspect there’s no real problem, but I’m not sure there’s no real problem.
    • Richard Feynman, in Simulating Physics with Computers appearing in International Journal of Theoretical Physics (1982) p. 471.
  • We choose to examine a phenomenon [Double-slit experiment] which is impossible, absolutely impossible, to explain in any classical way, and which has in it the heart of quantum mechanics. In reality, it contains the only mystery. We cannot make the mystery go away by “explaining” how it works. We will just tell you how it works. In telling you how it works we will have told you about the basic peculiarities of all quantum mechanics.
    • Richard Feynman, The Feynman Lectures on Physics: Commemorative Issue, Vol. 3 Quantum Mechanics (1989) 1-1, “Quantum Behavior.”