Tutorial 7 - Presentation

Contents

Presentation

Presentation of Written Work

Calculations

Exam Words

Why do Practical Work?

Key Practical Skills in Physics

Practical Assessment for AQA

Writing Reports
Further Experimentation

 

Presentation

Physics is a technical subject in which you are communicating your knowledge to others.  In your career, whatever you do, you will need to communicate in such a way that people understand.   There is no point in having the solution to a big problem unless you can tell others about it, in a way that others can understand. 

 

As a teenager, I studied Thomas Hardy for English Literature.  His Victorian writing style was impenetrable to my fifteen year old mind.  Forty five years later, I tried reading The Woodlanders again.  It was just as impenetrable and really got in the way of what should have been a good story.  Sorry, Mr Bowen.  I did try.  What I did get out of it was the picture of squalid little thatched cottages in Dorset, which are nowadays no longer the homes of agricultural or forestry workers.  Now they appear on Escape to the Country with large sports utility vehicles outside them.  Everything is tiny and twee, except the prices which are many hundreds of thousands of pounds.

 

This tutorial should give you some ideas about how you should present your work in a way that will help you to achieve your potential.  Good communication skills are vital not only in Physics, but also to sell yourself at interview.

 

Key points:

We will look at the various aspects of communication in Physics.

 

 

Presentation of Written Work

Communication

In the exam, there will be at least one question which asks you to give an account of a phenomenon (something that happens) in Physics.  In this, they will assess your written English, as well as the content of your account.  Whatever the career that you chose, the skill of writing good English is essential.  The standard of written English in many answers is not good.  While some people may dismiss the need for good English and clear presentation as elitist, the exam boards do not.  Nor do employers.  Follow this advice, and you will keep your written English clear:

 

 

Some common grammatical confusions are:

 

A badly word-processed document looks awful.  Plurals always end in ‘s’ without an apostrophe. There are spell checkers to check your spelling.  Make sure that it’s set to UK English.

 

Never use text-messaging.  The latter is fine for a mobile telephone, when messages were charged by the character.  It has no place in technical English (or any other language).

 

Question 1

Identify the spelling and grammatical errors in this passage.  

When U right sum thing about you're a level physics, you can be tempted 2 deep end two much on yore spell cheque.  It dose not pick up every miss steak.  Many student’s loose lots of mark’s coz there righting is pour.  Their knot thinking about what they Wright.  Sum times they rite rub is. 

 

Physics has lots of technical term’s.  Its gonna be import ant to make shore that their used prop early,   they will bee X-planed during the coarse.  4 example, wait is a fours, while currant is red form an amateur.  Chemist’s ewes destiny, witch is mess divided by volume.

 

Answer

 

This may sound a bit rich from my English teacher's worst pupil.  My written English is not perfect, but I try to write well.  So should you.  (I was hopeless at English Literature.  Sorry Mr Bowen.)

 

 

I have written "English" here, as most of my readers use the English Language.  If, for example, you are doing your Physics course in German, your German needs to be well written (or any other language, for that matter).  I have had students whose native language is not English.  What I have noticed is that often their spelling, punctuation, and grammar is better than that of natives speakers, although occasionally the structure of the English reflects that of their native language.  The same would apply to English speakers doing their studies in another language.

 

In universities, reports  are expected to be gender-neutral.  However this can give rise to inconsistent constructions like:

"The student wrote their results in a table".  The singular is mixed with a plural here. 

 

Perhaps a better way to write the sentence:

 "The students wrote their results in a table" or even "The student wrote its results in a table". 

 

The impersonal pronoun ("one") in English is not very good and can sound stilted and pompous.  Impersonal pronouns in German ("man") and French ("on") tend to work better in those languages.

 

Alternatively reports can be written in the passive voice ("The results were written in a table".).  At university reports are expected to be written in the passive voice.

 

If you are  keen on writing really good English, you can always read Strictly English by Simon Heffer.

 

 

 

Calculations

Calculations need to be set out logically; otherwise it is easy to get lost.  Follow this advice and you will not go far wrong:

 

Avoid writing stuff that is not mathematically correct, e.g.

s = ((20 + 30) × 10) ÷ 2 = 250 ÷ 10 = 25.  This is nonsense. 

 

Write it as:

s = ((20 + 30) × 10) ÷ 2 = 250 m

v = 250 ÷ 10 = 25 m s-1.

 

 

Tips for Calculations

1. Write down a formula or equation using standard symbols if possible.

2.  You may wish to write a "shopping list" for the quantities in the formula/equation  but this gets no marks                                                         

3.  Substitute values into the formula/equation without rearranging first (unless you know you won't make daft mistakes).

4.  Rearrange and calculate your final answer.    

Þ                    

5.  Write the answer using sensible significant figures and, if necessary, standard form.  Add the proper units.                                                            

 

Check that you have answered what the question actually asked for.  This may sound obvious, but many students give an excellent answer to a different question!

 

If you have done all this underline your answer:     

 a =11.1 m s-2


 

Exam Words

You need to understand the special meaning of the following words in exams:


 

Why do Practical Work?

In many schools, students' experience of practical work is limited.  Perhaps this is why:

 

 

For most physicists, experimental work is as important as theoretical work.  There were exceptions of course.  Ernest Rutherford was a brilliant experimenter, but not very good at maths.  Hans Heisenberg was a brilliant theoretical physicist, but was hopeless at the most elementary practical work.

 

Practical work:

 

All of these give evidence for employability skills as well.

 

Physics experiments have a reputation for not working properly and being rather difficult to interpret as a result. This need not be the case, if you do the following:

 

Key Practical Skills in Physics

There are certain skills that you will learn as you do your practical work.  You have probably done them anyway without thinking about putting a name to them.  But here they are anyway.

 

Follow instructions and Work with others

Some students find it hard to work with others.  However it is essential to do so, both at university and in employment.

 

This is NOT working with others:

 

Nor is this:

 

This study in indolence, taken from my car, was observed a few years ago on the A6 in Cumbria.

 

This IS working with others:

•  It means that each student takes responsibility for getting part of the experiment set up and data recorded. 

  You need to work co-operatively so that the task gets done quickly, and effectively. 

  While it’s most comfortable to do it with friends, you may find yourself having to work with someone you might not necessarily get on with socially.  Tough.

  Groups that get right idea about working together get the work done quickly and effectively.

 

 

Select and Use Equipment

This skill area concerns the choice and use of equipment for a procedure.


At AS level, you use standard laboratory equipment such as a digital multimeter and select the appropriate range.


In this picture, the 600 volt AC range has been chosen. You can see that there are a lot of other ranges that can be chosen.

 

 

Needless to say, the equipment has to be used correctly, safely, and appropriately.
 

 

Organisation and Safety

Parkinson’s Law, coined by Cyril Northcote Parkinson (1909 – 1993), tells us that:


Work expands so as to fill the time available for its completion.

 

In other words a lot of time can be wasted.  And this happens frequently in practical work.  One person (if that) does the work, while others watch.

 

Here are some guidelines for effective organisation:

 

Safety of all students must be the first priority.  There is no observation that is so important that students are put at risk to obtain it.  The risks in a school or college physics laboratory are very low, but students still have a responsibility to look after their own safety and that of others.

 

Risks in physics experiments include:

Safety should always be considered before carrying out any experiment.


If equipment is faulty, it must be reported to the teacher. It should go without saying that no action should be taken to compromise safety by abusing equipment or doing unauthorised experiments.


You should get into the habit of making your own risk assessment, even though your teacher will have carried out a risk assessment previously. In this, you should consider:
 

It is also worth remembering that laboratory equipment is very expensive.  And you could end up being billed for it...

 

 

Practical Assessment for A-level Physics (AQA)

For the new linear A-level syllabus, you will have to hand in a portfolio (file) of your laboratory work when you reach the end of the second year of A-level.  There is no such requirement to pass AS level.  In your centre, the policy may be that you will have to pass AS level to progress to A-level.  Therefore you will be expected to maintain the practical skills portfolio during the AS year, and do the first year set practicals.  There will be examination questions that are based on data analysis that involve the set practicals.  They may well cover material from other experimental work.

 

The six set experiments for AS are:

The six set experiments for A level are:

Images from the AQA A-level syllabus

 

If your centre does the two year linear syllabus without doing AS level, you may find that you do these set practicals in a different order.  It depends how your tutors organise their scheme of work.

 

This is NOT the only practical work you will be doing.  Practical work is an important part of your class-work, and will form much of your class-work mark (depending on the policies in your Physics Department). 

 

Note that other syllabuses have different arrangements.  Your tutor will advise you.

 

Writing Reports

In your portfolio, you will need to write reports in the traditional way.  The idea of this is to:

 

There are frequent questions in the examinations on practical techniques, so if you can remember them, you are at a strong advantage.

 

You should aim to enable your reader to follow your instructions and get the same results that you did.

 

 

Introduction

You should give a brief explanation of what you are setting out to do, and how it links in with the theory.  For example, if you were finding the resistivity of a piece of wire, you would explain that the gradient of the graph can be found from the formula:

Therefore the gradient of a graph of resistance against length is r/A, so resistivity can be worked out by multiplying the gradient by A.

 

Apparatus

This needs to be a list of the equipment that you are going to use.  You need to write not only the list, but also the ranges.  If you were going to measure 6 volts, you will need to state that you were using the 20 volt range on the multimeter.  You should also state the precisions, e.g. +/- 0.1 V.

 

Diagram

You do not have to be a good artist to draw a good diagram.  Diagrams should show the reader how the equipment was put together, so that the reader can assemble the equipment to do the experiment.  This diagram is taken from a report done by an A-level student:

 

 

Pitiful, isn't it?

 

1. Diagrams should be done in pencil or drawing ink.
2. Use a ruler, please.
3. Make the diagram clear.
4. Label it.



Some students show pictures of each individual piece of apparatus, e.g. a stopwatch. This is meaningless.

If you are doing a word-processed report, you should learn to use graphics, e.g.:
 

 

This diagram was made using MS Office graphics.  I find that PowerPoint graphics are easier to use than those in Word.  Many of my graphics on this site have been put together using PowerPoint.

 

If the diagram is complicated, make it large, so that the complex bits can be seen, as in the picture above.

 

Method

This should be a list of instructions so that the student who missed the lesson can do the experiment following your instructions and get a good set of results.  The instructions don’t have to be complicated, or a great piece of literature.  The best method is a set of instructions in your own words, showing your own understanding.  You should mention whether there were changes in the original set of instructions.  For example, you may have used 4700 ohm resistors instead of 3300 ohm resistors.

 

It is important to use good English and clear presentation.

 

A mindless copy of a generic worksheet always got very few marks from me.

 

Results

You must produce a neat table of results boxed in.  This is an example:

 

This one is lifted from a past Physics 6 paper.  The student has filled in the data for the last couple of rows.  It is here to show how a table is set out with data that have been collected (or harvested) and data that have been processed from the harvested data.  It shows the way the headings should be set out.

 

Question 2

(a) Which data have been harvested?

(b) Which data have been processed?

Answer

 

Units are put into the column headings along with the quantity.  Note that the quantity is separated from the units by a solidus (/). 

 

The solidus indicates the division (÷) of a physical quantity by its unit, thus what follows is a pure number.  For example, ‘V / mV = 340’ literally means 340 is the value of V divided by mV.  Using ‘V / mV ‘ as a table heading is logical and correct in a way that V (mV) is not.  This may seem pedantic, but it's good practice.

 

Note also that physics codes in word-processed documents are written in Times New Roman font and in italics.  The units are in normal font.  You wouldn't get marked down for not doing this, but it's a good idea to get into the habit.  If you are hand-writing the document, it doesn't matter.

 

There should be sufficient data points to get a straight line.  7 data points is reasonable.

 

The number of significant figures should represent the precision of the instrument.  So in this case, the ruler to measure x is to the nearest 1 mm, so it is reasonable to put down the data to three significant figures.

 

Graphical Skills

We have covered these in previous tutorials.  Just to remind you:


1. Always use a sharp pencil and a ruler.
2. Draw the axes
3. Label the axes with the quantity and the units
4. When you plot Quantity 1 against Quantity 2, you put Quantity 2 on the horizontal axis.
5. Look for the highest value in each range. You calibrate (put numbers on) your axes to the nearest convenient step above your highest value.
6. Use a sensible scale.
7. Plot your points with crosses (+ or ×). Points get lost.
8. Join your points with a line, but not dot-to-dot!
 


It can be difficult to decide whether a set of results is a straight line or a curve. If it’s clearly a straight line, draw your line of best fit with a ruler. If the graph is a curve, then try to make a smooth curve. A flexi-curve can help you with this.

If a point is way out from the rest, then it’s probably an anomalous result.  If you can, recheck the data or do that part of the experiment again. If not, ignore it.

 

Analysis
At A-level you will be expected to carry out some kind of analysis of your data.  This will become more searching and in depth as you become more experienced.  The sort of things you will almost certainly be asked to do include:

On the worksheet your tutor gives, there will be questions that will get you to discuss various aspects of your experiment.  Answer these fully.

 

Conclusion

The conclusion is a summary paragraph that shows:

 

The table below shows how I would mark a practical report for my students.  Your tutor may use something similar:

 

Section

Content

Marks

Total

Notes

Introduction

Context of practical

1

3

 

Summary of what will be done

1

Theory

1

Apparatus

List of apparatus

1

3

List needs to be the apparatus actually used.

With ranges

1

Precision stated

1

Diagram

In pencil/drawing pen

1

4

Diagram needs to be produced by the student.

With a ruler

1

Labels with leader lines

1

Clear

1

Method

Method written in own words…

1

5

A copy of the work sheet will get zero marks.

 

Slovenly work will be penalised.

…with clear steps…

1

…in a logical order…

1

…in good English…

1

…and with good use of technical terms.

1

Results

Minimum number of results

1

5

If repeats are not appropriate, marks will be adjusted.

In a neat table

1

With headings and units

1

With repeats

1

Data recorded to appropriate precision

1

Graphs

Large graph

1

8

Scales should be in steps of 1, 2, 5, or 10.

 

Graphs to be drawn by hand.

 

Axes labelled with quantity and units.

1

Sensible scales

1

Plot

2

Error bars

2

Line of best fit

1

Gradient

Large triangle

1

4

Smallest side of the triangle should be at least 8 cm

Rise and run values noted

1

Gradient calculated…

1

…with units.

1

Analysis

Uncertainties identified…

Questions will be set to discuss these.  Marks are variable.

…and quantified.

Limitations identified

Improvements suggested

Conclusion

What has been learned.

Questions will be set to discuss these.  Marks are variable.

 

How it links with the theory.

 

The final total mark was always a multiple of 5 (e.g. 45 or 60).  I didn't like marking out of a number like 56, but that was just me.

 

Further Experimentation

A classic GCSE experiment is where you investigated the factors that affect resistance:

Most likely you will have investigated resistance against length.  You will do a similar experiment in the first year.  This time you will find out the resistivity and compare the result with the data-book value.

 

In some exam papers, you may be asked a question on what further experiments could be carried out to investigate a problem.  Do NOT write "take repeat readings" or "use more accurate equipment", or "use a data-logger" .  You will get no marks.  The question is asking you to think about other factors to investigate, for example the relationship between area and resistance, or even diameter and resistance.

 

When you are asked about further experimentation, you need to discuss a method.  It should use apparatus available in a school or college Physics lab.  It should be a set of written instructions that another student could read and use to do the experiment.  The best answers show what ranges to use for meters and possibly the specifications of the materials you are going to work with ("I will use constantan wire of 1.5 mm diameter").

 

For another example, you may have carried out an experiment on the half life of a capacitor discharge through a resistor (which you will do in the second year).  You may have plotted the exponential discharge graph for a start voltage of 6 V.  You have found the half life of the discharge.  You may want to investigate whether doubling the voltage affects the half-life.  So you would say that you would use the same capacitor and resistor, but make the start voltage 12 V.

 

To improve an experiment, you need to address how you would reduce uncertainty to get data that are more reliable.  For example, in one experiment that you will do in Year 2 (A-level year), you investigate the relationship between pressure an volume (Boyle's Law).  One way of doing this is to put weights on the plunger of a plastic syringe:

 

 

The picture shows the set up.  Plungers on this kind of syringe have a lot of friction.  So there is considerable uncertainty with the force that needs to be applied to pull the plunger out.  10 ml syringes are rather small, so the volume is small.  Therefore there is more uncertainty.  Additionally the syringes are held in clamps and if you screw the clamps too tightly, you will deform the syringe.  Too loose, the syringes fall out.   An improved experiment would use glass syringes, which have a larger volume and the friction is lower.  You would not want to put a glass syringe into a set up like this, as if they fall out and break, it's expensive.  So an alternative and improved way of doing the experiment is:

 

 To reduce the risk of breakage, you may want to place a pad underneath the slotted mass.

 

Will this graph get full marks?
Here are some graphs given as examples from the AQA booklet that gives guidance on practical work.

Note that in these examples there are no quantities or units on the axes (which would lose you marks). Nor are there error bars

This graph is acceptable:
 

Image from AQA

 

This graph has well-spaced marking points and the data fill the paper. Each point is marked with a cross (so points can be seen even when a line of best fit is drawn).

Now we will look at some other graphs.  Think about these (with a classmate if possible) and come to a decision on whether the graphs will get you the marks. Remember:


•  No quantities or units are on the graphs.
•  No error bars have been put in.

 

Question 3

Image from AQA

 

Draw the line of best fit.  Is this graph acceptable for full marks?

Answer

Question 4

What is wrong with this graph?

Image from AQA

Answer