 # Category: AQA Unit 1 Particles/ Quantum/ Elec

## Unit 1 AS Exam Past Papers

If you need the 2009-2011 Papers here they are…

Unit 1 Exam Papers

## Why do thick wires have lower resistance?

This text has come from Furry Elephant so I don’t take credit but it is cool, read and have a think…
Even the most apparently reputable sources of information are sometimes full of misconceptions. The BBC manages to demonstrate several all at the same time with this terrible animation trying to explain why thicker wires have a lower resistance than thin ones.
The main argument is that a thick wire has ’more space’ for the electrons to move around in than a thin wire. But wires are made from atoms – that’s where the free electrons come from. So thicker wires have more atoms and so no more empty space (per cross-sectional area) than thin ones. Another implication of the animation is that the wires are like empty tubes. This suggests that the electrons come from the battery as a sort of source rather than already being there everywhere in the circuit. The final problem is the speed of the electrons. Since the animation shows a longer path for the electrons in the empty thick wire their speed must have increased. In fact, the opposite is the case. Electrons travel slower in thick wires.

For a copper wire (at a given temperature) the speed of the electrons depends only on the voltage across it. Imagine a three-lane road and a single-lane road with cars all going at the same speed. More cars pass per second in the wider road even though the speed is the same. More cars (charges) per second means higher current for a given voltage and so smaller resistance.

Since current is the same around a simple series circuit the charges have to go faster where the wire is thinner. Faster charges mean more interactions with the ionic lattice per second and so higher resistance.

This is a topic which introduces the detail of the atom, the idea of stability, the photon model E = hf, antiparticles and the interactions of particles. There is quite a lot of wordy detail and basic facts to learn with a small number of calculations such as specific charge or E = hf to cover. Also make sure you know what an electron volt is and how to derive it from first principals. Energies may also be expressed in Joules or MeV so be sure on that one as well. Also you must visit https://www.particleadventure.org/ to read around the first three topics. If you don’t you will fail the exam! But a word of caution you will not need to know everything on the site. The AS Physics Exam does not cover every particle in the universe so check the specs!

#### Main Resources….

01 Matter and Rad Student Booklet

Inside the atom

1.1 Dream Journey Inside The Atom  (cartoon on the atom)

Stable and unstable nuclei

1.2 More on Neutrinos  (information sheet)

Photons

1.3 Lasers Extension (if you want to think more deeply about lasers)

Particles and antiparticles

1.4 Antimatter (cartoon on Antimatter)

1_4_Chronology of particle physics

How particles interact

1.5 Feynman Diagrams Worksheet (problems & solutions for Feynman Diagrams)

1.5 The Big Bang (Cartoon on Big Bang Theories)

1.5 Higgs Boson (some detail on what is the Higgs Boson)

## Northern Lights | Twig Secondary

Discover how the chemical reactions that produce the extraordinary colors of the Northern Lights have their origins in outer space.

Find out more about Twig Secondary: http://www.twigsecondary.com

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## AS Chapter 1 Matter and Radiation

This is a test designed to check if you understand Chapter 1 of the work you have completed. Only attempt this quiz when you have revised or you will not get a top score. When you get a score you are happy with let you teacher know so they can put it in their markbook.
Congratulations - you have completed AS Chapter 1 Matter and Radiation. You scored %%SCORE%% out of %%TOTAL%%. Your performance has been rated as %%RATING%%
 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 End

## 2 Quarks and leptons

This topic is about learning what is inside a nucleus and essentially how does that make an atom behave. You really need to learn a lot of basic facts.  You can also find loads of youtube movies, just search for the key terms and you will learn lots of things.

#### Main Resources

02 Quarks and Leptons

02 Quarks and Leptons Student Booklet

2.1 The particle zoo

Particle Physics Reference Booklet (Particle reference sheet)

2.2 Particle Sorting

2.2 ParticleAccelerators  (Information sheet from Cern on Accelerators)

2.2 LHC (Information sheet from Cern on Accelerators)

2.5 Conservation rules

Strangeness (Strangeness Summary)

## Cloud Chamber Cosmic Rays

Pb210 Source showing background alpha and neutrino, muons and other cosmic rays in a cloud chamber.

## AS Chapter 2 Quarks and Leptons

This is a test designed to check if you understand Chapter 2 of the work you have completed. Only attempt this quiz when you have revised or you will not get a top score. When you get a score you are happy with let you teacher know so they can put it in their markbook.
Congratulations - you have completed AS Chapter 2 Quarks and Leptons. You scored %%SCORE%% out of %%TOTAL%%. Your performance has been rated as %%RATING%%
 1 2 3 4 5 6 7 8 9 10 End

## 3 Quantum phenomena

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

03 Quantum Phenomena Part A

03 Quantum Phenomena Part B

03-QM-Student-Booklet

Textbook-Extract

spectra

AS Physics Unit 3 Exam Questions

## 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.

There is ...
a worksheet that accompanies this experiment so you can attempt the analysis yourself.
Get it here: https://www.tes.com/teaching-resource/planck-s-constant-experiment-worksheet-12336895

In the follow up video (https://youtu.be/etsxej_nTGI) I analyse the results and calculate the value of Planck's constant yielded by the data. The spreadsheet used for analysis is available here: https://www.tes.com/teaching-resource/estimate-planck-s-constant-analysis-spreadsheet-12340515

* 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.

## 12 Electric Current

This is the basic introduction to current flow and circuits. Really this unit is just an extension of GCSE Electricity with some harder problems using the same rules. Also you will need to remember how each component works and be able to interpret a VI graph. Always remember to check your gradient. Since V=IR a graph of V – y-axis and I – x-axis shows R as gradient. The other way around which is how we tend to do exp shows 1/R it does matter.

Circuit Construction Kit (phet animation)

12 Electric Current (lesson PPT)

12 Electric Current Student Booklet (lesson notes for section)

12.1 Current and charge

aluminium (Electrolysis of Aluminium Animation)

fluid_electrolysis (Electrolysis of Copper Chloride E=VIt)

12.2 Potential difference and power

Electron Speeds Worksheet (extension – challenge!)

Electricity Calculations & Sig Figures….. I would advise all of you to look at this tutorial this week before you do the unit homework…   https://www.chem.sc.edu/faculty/morgan/resources/sigfigs/index.html . An example is V = 12V, Resistance = 62Ω. If you work out the current through the resistor as V = IR changes to V/R = I = 12V/62 Ω = 0.193548A.  The original data is 2 sig figures so you should quote the answer to this as well. Hence…

0.2A  – Wrong                0.19A – Correct          0.193548A  – Wrong

12.3 Resistance

resistivity (animation) Use this to think about how atoms actually look inside a metal. Then imagine a drift of electrons through this.

4_3_Investigation (Practical Investigation & Worksheet)

4_3_Resistance Worksheet 1 (problems)

4_3_Resistance Worksheet 2(problems)

4.3 Resistance Networks Worksheet (problems)

Resistivity example data (this is a spreadsheet from practical with example graph)

Model (phet – resistivity of a wire)

Ohm’s Law Model (phet)

12.4 Components and their characteristics

4_4_Graphs Worksheet (graphing problems)

LED Forwards Bias Data (Excel) Data and graph from logger of diode in forwards bias with resistor inline.

oven temp sensor (How Science Works information sheet on thermistor at work)

Diode Problem (extra problem to look at) This one is often used in the AS exam when looking at diodes

Youtube Video Tutorials “Electricity” – Steve4Physics

## Van De Graaf Electrical Current

This quick demo shows the idea of sparking and how fast the spark can move between the electrodes and also how to the frequency of spark changes due to lower ...air resistance as you get closer to to he dome.[+] Show More

## 13 Direct current circuits

This section is about applying some more advanced rules to circuits that build on your GCSE skills. The trick is to realise that you must be 100% logical and treat it as a mathematical exercise. If you set up the problems correctly then you cannot go wrong. Take note of these things that you must be able to do…

1. Make sure you treat current and pd as having a direction.
2. Learn how to apply reciprocal equations for 1/R for resistors in parallel
3. Learn what the gradient and intercept mean on an Internal Resistance circuit graph
4. Remember that a power source is a “real source” and will get warm so lose energy! A 3V cell does not output 3V!
5. When thinking about potential dividers the trick is to realise that current is the same through each resistor. So setup two equations for V for each then I is the same for both!

13 DC Circuits (Main PPT)

13 DC Circuits Student Booklet (student booklet notes)

13.1 Circuit rules

5_1_kirchoffs laws (problem sheet)

5_2_Practical_investigating_resistors (Practical on Resistors)

5_2_practical_cons_energy (Practical sheet proving Kirchhoff’s laws)

resistor_cube_problem (Extension – 3D resistor cube problem – for fun!)

13.3 Emf and internal resistance

Internal Resistance Calculator (Hyper Physics)

5_3_EHT_Practical_Demo (teacher demo with results to graph)

5_3_Internal_Resistance Problems (probkems sheet)

5_3_IR_of_Battery variable current method (practical method 1)

5_3_IR_of_Cell adding bulbs method (practical method 2)   Results 3 Cells (excel results)

5_3_IR_Practical_Higher_Ability

13.4 More circuit calculations

5_4_Investigation_cell_combinations (Crucial practical which explores how PD behaves for series & parallel)

13.5 The potential divider

5_4_Potential_Dividers Worksheet

## Kirchhoff's Laws - A-level Physics

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00:00 Kirchhoff's 1st & 2nd laws
02:11 2nd law worked example

## 6 Alternating currents

This section is partly about learning to use and oscilloscope and partly about working out RMS currents and converting between A.C. and D.C. You must learn how to do both.

AS Physics Unit 1_6 (main notes / PDF)

6.1 Alternating current and power

Rectification (extension)

6.2 Using an oscilloscope

6_2 Practical Using OSC  (you need this to help you work the osc)

6_2_Oscilloscope Handbook (information for using OSC)

6.2 Oscilloscope Problems (worksheet)

6_2 Using an Osc (extension)

virtual osc (Very good virtual Oscilloscope – download, unzip and run in Internet Explorer. Use for 6.2 lesson)

Youtube Video Tutorials “Electricity” – Steve4Physics