# Category: A Level Physics Chapters

## Oxford Uni PAT tests and Prep

This is a list of files that I have built up over the years from various sources which will help you prepare for PAT tests for Oxford. The answers are not mine but clearly at Oxford don’t provide answers are one solution done by experienced Physics teachers which will help you.  I don’t have any more answers or files than those listed here.

#### Official PAT Exams 2006 onwards

 pat-2008pat-2008-answerspat-2009 solutionspat-2009pat-2009-samplesolutionspat-2010pat-2010-samplesolutionspat-2011 solutionspat-2011pat-2012 solutionspat-2012pat-2013pat-2013-samplesolutionpat-2006pat-2007 solutionspat-2007 pat-2016pat-2017 Solutions Q18 onlypat-2017 Solutionspat-2017pat-2018 Solutionspat-2020 Solutionspat-2020pat-2014 Solutionspat-2014pat-2016 Solutions

#### Un-Official Practice Exams (No answers given) – from “The Science Doctor”)

• Physics/Engineering at Oxford: PAT
• Engineering at Cambridge: ENGAA
• Natural Sciences at Cambridge: NSAA

2018 Breakdown of question topics

1 Mechanics

2 Electricity

3 Waves

4 Area and Volume of Shapes

5 Differentiation Integration and Series

6 General Physics

7 General Maths

## 30 Relativity

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.

#### Resources

30 Relativity

30 Relativity Book

A2 Relativity Practice Questions

A2 Relativity Timed Assessment

## Relative Motion and Inertial Reference Frames

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!

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## 29 Wave Particle Duality

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.

#### Resources

29 Wave Particle Duality

29 Wave Particle Duality Book

A2 Wave Duality Prac Questions

A2 Wave Duality Timed Asssessment

SEM Simulation

## Liquids Conduct Heat Poorly

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

## 28 Discovery of the Electron

#### Resources

28 Discovery of Electron

28 Discovery of Electron Book

A2 Discovery of Electron Timed Assessment

## Thermionic Emission Explained - The Cathode Ray Tube - Physics

When a metal wire is heated in a vacuum, electrons are 'boiled' off the surface. This effect is called thermionic emission.

Discover more physics tutorials at: https://gcsephysicsninja.com

## Space Revision

If you wish to do a bit of revision or learning on KS3, 4 or 5 space. Then try some of the resources here, you can have a PPT or PDF.

Feel free to use for school use, but all images are copyright so no profit or derivatives which you sell!

## Turbo Chargers – Amazing

Turbo gives petrol cars a boost as diesel faces backlash – https://www.bbc.co.uk/news/business-34731463

# Turbo gives petrol cars a boost as diesel faces backlash

Looking at Kia’s new Proceed T-GDi GT-Line, with its sporty looks and handling, you might expect a big, thirsty engine under the bonnet.

Instead, it has a frugal three-cylinder 1.0 litre petrol engine that can still deliver 0-62mph (0-100km/h) in 10.7 seconds, nearly 60 miles to the gallon, and CO2 emissions of 115g/km.

A few years ago, this kind of performance would’ve been considered outstanding.

Thanks to turbo tech, these traditionally-fuelled internal combustion engines are now offering better fuel economy and lower emissions, without comparable loss of performance.

And in light of the recent Volkswagen diesel emissions scandal – and tighter emissions regulations worldwide – company car fleet directors are taking note.

“Diesel has emerged as the dominant fuel type for company cars, as a result of great fuel efficiency, performance and low cost of ownership under the government’s CO2 emissions based tax regime,” says Gerry Keaney, chief executive of the British Vehicle Rentals and Leasing Association, whose members own or fleet manage more than three million cars in the UK.

“But the diesel proportion of new registrations has been falling gradually for some time, as modern petrol powered cars have become better at delivering similar benefits, and we expect this trend to gather pace.”

In the UK, even company car buyers now see downsized petrol engines, many emitting around 100g/km CO2, as a viable, efficient alternative to diesel.

This is not just down to “anti-diesel sentiment”, says Al Bedwell, director, global powertrains at LMC Automotive. “It has more to do with petrol getting better and staging a fight-back, especially in small cars in Western Europe.”

Manufacturers such as Ford, Opel/Vauxhall, Hyundai and Volkswagen are all offering similarly downsized petrol engines these days, many emitting around 100g/km of CO2.

In Europe, diesel’s share of the market is set to drop from 53.3% of the market in 2014 to 51.5% in 2015, says Mr Bedwell, then continue sliding to 35% by 2020.

## Power boost

Turbo chargers are traditionally associated with diesel engines, which needed a boost to give them more oomph. They weren’t “much fun to drive” without them, says Guillaume Devauchelle, head of innovation and science at automotive technology company, Valeo.

And the relative cost of adding turbo to an expensive diesel engine was lower, he explains.

But turbos are now increasingly infiltrating petrol engines because they deliver dramatic emissions reductions and improvements in fuel economy, without sacrificing performance, says Craig Balis, chief technology officer of Honeywell Transportation Systems, the world’s largest turbo maker.

A two-litre turbo-charged four cylinder petrol engine can match the output of a three-litre naturally aspirated V6 petrol engine, he says, so “the technology we have is really a no-compromise solution”.

Turbos work by using the engine’s exhaust gas to drive a turbine, which in turn drives a compressor, which compresses air. This air is then forced into the combustion chamber where it mixes with fuel to create additional power.

This means the engine won’t have to burn so much fuel to deliver the same output.

“Our turbos for passenger vehicles have turbines that spin at 200,000-300,000 revolutions per minute (rpm), generating temperatures of up to 1,000 degrees Celsius, so the metal is literally glowing red,” Mr Balis says.

By comparison petrol engines operate at just 6,000-7,000 rpm and diesel at 5,000-6,000rpm.

To cope with such extreme speed, pressure and heat, turbos need to be incredibly robust, so Honeywell is using ball bearings and other technologies that have been developed for military aircraft by the company’s aerospace division.

The turbos are also coupled with intercoolers that cool the airflow and increases its density as it is supplied to the engine, and with oil cooling systems that prevent overheating.

## Instant power

Turbos are often combined with direct or indirect fuel injectors and variable valve lift or timing systems to make the process even more efficient.

Electrified superchargers, which compress air for just a few hundred milliseconds to add brief low-end torque until the turbo charger kicks in, will also hit the market in the next few months.

Over the next five years, we’ll go from about a third to around half the cars sold having turbo chargers, and the growth will continue. We call this the ‘golden age of turbo’

Terrence Hahn, Honeywell TS

E-chargers, or e-turbos, will transform the driving experience, believes Mr Devauchelle, as they eliminate what’s called turbo lag – that slight delay in power boost you experience after pressing the accelerator.

“The turbo increases the engine’s maximum power. The e-charger gets you there even quicker,” he explains.

As such, e-turbos may rival established twin-turbo technology, where a small turbo takes care of the early stages of acceleration before the second turbo takes over.

The e-turbos’ batteries can be recharged in different ways, for instance by capturing energy during braking, explains Mr Hahn.

With enough electric power, e-chargers could take over more and more of the work done by the turbo.

Eventually carmakers will redesign vehicle architecture, moving from standard 12-volt batteries to higher voltage systems.

Forty-eight volt architecture is emerging in luxury cars with many electric components, but e-chargers can also run on 12-volt batteries if they are only required to deliver brief boosts, explains Mr Devauchelle.

## ‘Golden age of turbo’

“Petrol power is moving from naturally aspirated engines to turbo charged engines at a faster rate than ever before,” says Terrence Hahn, president and chief executive of Honeywell Transportation Systems.

“Over the next five years, we’ll go from about a third to around half the cars sold having turbo chargers, and the growth will continue,” he predicts.

“We call this ‘the golden age of turbo’.”

But there is no silver bullet as carmakers continue to grapple with ever-stricter emissions regulation, coupled with huge penalties for non-compliance.

Any number of combinations of e-chargers, turbo chargers, multi-stage boosting, fuel injection, variable valve systems, and combustion-electric hybrid technologies are being explored.

“During 30 years in the industry, I have never before seen so much diversity,” says Mr Devauchelle.

“Nobody can afford the penalties.”

## What is Newton’s second law of motion?

What is Newton’s second law of motion?

https://www.gu.com/p/3zpeb