Cambridge International Examinations Paper 5

7/29/2019 Cambridge International Examinations Paper 5

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Compiled by

Imran Mirza

Sc Physics, PGCC,

Scoland, Uk

CAMBRIDGE INTERNATIONAL EXAMINATIONS

2013-2014

A-level PhysicsThis booklet covers CIE A Level Physics Paper 5Imran Mirza

Planning

AnalysisAnd

Evaluation


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Exam tips for Planning, Analysis and Evaluation paperBy

Imran Mirza

Don't rush........

Three golden rules........

1. Read the question

2. READ the question

3. Answer the question

Make sure that you do not do what so many students do......they see a 'key c word like 'magnetic

flux' in a question and write down everything they know about magnetic flux, as fast as they can.

Take your time..........there is more than you think!

IT is forbidden...........

Marks will not be awarded to answers which are unclear. Try to write a reason for your choice of

apparatus and.....

Don't be intimidated........

Don't be intimidatedby long questions...... they quite often are easier and quicker questions than

the shorter ones...........

Do as you are told!

Write the apparatus along with reason. Remember that not all of the apparatus in the

provided list is essential for the investigation- You may use other standard equipment that is

needed/ available in the laboratory work.

Draw a neat and labeled diagram of the arrangement of apparatus which you propose to

use. Space is available for this in the question paper.

Write procedure in steps wise and high light control of certain variables to carry out a valid

investigation.


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Write the safety aspect (where appropriate) of your investigation. Sometimes the question

specifically ask for these to be mentioned (e.g. in a design question where radioactive sources

are used) but any relevant safety point can be rewarded.

A number of marks are reserved for what is considered to be good further or relevant detail.This is because your answers depend so much on the approach which has been taken!

Keep in mind!

Some students write copious amounts about the 'conclusions* of their investigation and draw

sketch graphs of what the result might be. Since no experimental work has actually been carried out

it is not possible to reward any work of this kind

Good marks can often be gained by giving relatively short concise answers. Keep

an eye on the time (watch)

Blank paper does not score

Do not leave anything out! If you have no idea what the question is on about....... GUESS. You

never know.... You just might be right! .........and don't give up........ Work right through to the end

of the exam. Cross checking your answers......... keep thinking........ New ideas may draw!

Stay Cool......

Nobody knows everything..........

.......so don't panic if a question is not well answered.

........just do what you can........

The important thing is that you walk out at the en4 thinking.........I DID MY BEST


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Ins truct ion s In the Syl labu s

Paper 5

This paper will consist of two questions of equal mark value (15 marks each) based on the practicalskills of planning, analysis and evaluation. The examiners will not be restricted by the subject content.Candidates will answer all questions. Candidates will answer on the question paper.

Paper Type of paper Duration Marks Weighting5 Planning, Analysis

& Evaluation1 h 15 minutes 30 12%

Mark scheme for Paper 5

Paper 5 will be marked using the broad mark scheme below. The expectations for each markcategoryare listed in the sections that follow.

Question 1

Skill Breakdown of marksPlanning 15 marks Definin the roblem 3 marks

Methods of data collection 5 marksMethod of anal sis 2 marksSafety considerations 1 markAdditional detail 4 marks

Question 2

Skill Breakdown of marksAnalysis, conclusions andevaluation

15 marks A roach to data anal sis 1 markTable of results 2 marksGra h 3 marks

Conclusion 4 marksTreatment of errors 5 marks

Planning

Defining the problemDefining the problemCandidates should be able to:

identify the independent variable in the experiment

identify the dependent variable in the experiment

identify the variables that are to be kept constant.

Methods of data collectionCandidates should be able to:

describe the method to be used to vary the independent variable

describe how the independent and dependent variables are to be measured describe how other variables are to be kept constant

describe, with the aid of a clear labelled diagram, the arrangement of apparatus for theexperiment and the procedures to be followed.For full marks to be scored in this section, the overall arrangement must be workable, that is,it should be possible to collect the data required without undue difficulty if the apparatus wereassembled as described. The measuring instruments chosen should be fit for purpose, in that theyshould measure the correct physical quantity to a suitable precision for the experiment.


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Method of analysisCandidates should be able to:

describe how the data should be used in order to reach a conclusion, including details of derivedquantities to be calculated and graphs to be drawn as appropriate.

Safety considerationsCandidates should be able to:

assess the risks of their experiment

describe precautions that should be taken to keep risks to a minimum.

Additional detailUp to four marks will be available for additional relevant detail. How these marks are awarded willdepend on the experiment that is to be planned, but they might, for example, include marks fordescribing how additional variables are to be kept constant, or for a diagram of a circuit needed tomake a particular measurement, or for additional safety considerations.

j

Analysis, conclusions and evaluationApproach to data analysisCandidates should be able to:

rearrange expressions into the forms y = mx + c, y = axn, and y = ae

kx;

plot a graph of y against x and use the graph to find the constants m and c in an equation ofthe form y = mx + c

plot a graph of log y against log x and use the graph to find the constants a and n in anequation of the form y = ax

n;

plot a graph of In y against x and use the graph to find the constants a and k in an equation ofthe form y = ae

kx;

decide what derived quantities to calculate from raw data in order to enable an appropriategraph to be plotted.

Table of resultsCandidates should be able to:

complete a table of results following the conventions required for Paper 3; Where logarithms arerequired, units should be shown with the quantity whose logarithm is being taken, e.g. In (d/cm). Thelogarithm itself does not have a unit

GraphCandidates should be able to:

plot a graph following the conventions required for Paper 3; show error bars, in both directions where appropriate, for each point on the graph; draw a best-fit straight line and a worst acceptable straight line through the points on the graph.

The worst acceptable line should be either the steepest possible line or the shallowest possible line thatpasses through the error bars of all the data points. It should be distinguished from the best-fit line either

by being drawn as a broken line or by being clearly labelled.

ConclusionCandidates should be able to:

determine the gradient and y-intercept of a straight-line graph; derive expressions that equate to the gradient or the y-intercept of their best-fit straight lines; draw the required conclusions from these expressions. The

conclusion required will normally be the value of a constant


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Treatment of uncertaintiesCandidates should be able to:

convert absolute uncertainty estimates into fractional or percentage uncertainty estimatesand vice versa

show uncertainty estimates, in absolute terms, beside every value in a table of results

calculate uncertainty estimates in derived quantities

show uncertainty estimates as error bars on a graph estimate the absolute uncertainty in the gradient of a graph by recalling that absolute

uncertainty = gradient of line of best fit gradient of worst acceptable line

estimate the absolute uncertainty in the y-intercept of a graph by recalling that absoluteuncertainty = y-intercept of line of best fit y-intercept of worst acceptable line

express a quantity as a value, an uncertainty estimate and a unit.


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Physics Paper 5 : Sample SolutionQ) The Properties of many magnetic materials are affected by temperature. One effect is the lossof permanent magnetism when the temperature of the magnetic material exceeds a particularvalue. This Temperature is known as the Curie Point.

Design an experiment to investigate how the magnetic field strength of a magnet depends on thetemperature of the magnet in the range from 0-200 degree Celsius. (May/June 2002)

Sol:-

Apparatus:1)Tongs

2) Rubber gloves and protective goggles

3) engine oil ( boiling point > 250 degree Celsius)

4) Digital Thermometer

5) Calibrated Hall Probe with Tesla Meter and a permanent steel magnet

6) Trough

7) Electric Heater with thermostat

8) Dry ice and an insulated container for its storage

Variables:

Independent: Temperature would be the independent variable since its effect on magnetic flux density need to be

observed and will be changed by the observer.

Dependent: Flux density

Control: To ensure a fair test, make sure no other magnetic material is near the apparatus setup; Carry out the

experiment at room temperature. Also the distance of hall probe should be constant from the magnet, otherwise

different values would be obtained for the same temperature and fair test cannot be ensured.

Procedure :

Fill the trough with engine oil and insert the probe/sensor of digital thermometer in it. First add dry ice and let the

temperature fall to 0 degree celsius. Now immerse the permanent steel magnet inside the oil and allow it to remain in

for 10 minutes. Add the dry ice after every 2-3 minutes to ensure the temperature is maintained at 0. After the time

period , take out the magnet with tongs and position the hall probe w/ tesla meter such that it is normal to magneticflux. Record the value of flux density obtained and repeat the procedure for the same temperature. Now turn on the

electric heat and maintain temperature at 50 degree C. Immerse the magnet, repeat the same procedure and calculate

the value of flux density obtained. Repeat it for temperatures of 100, 150 and 200 degree C besides that for 0 and 50

which has already been done.

Tabulate the results obtained :

Temperature/*C (Flux Density/T)1 (Flux Density/T)2 (Flux Density/T)Avg

0

50

100

150

200

Draw a graph of Flux Density ( Y-axis) against Temperature( X-axis)Observe the general trend of the plotted line. If a general decreasing trend is obtained , preferably linearsuch that it meets the x-axis at a specific point (Curie point) , the relationship is proved.

Improvements and Safety ConcernsAlways wear the protective goggles and rubber gloves to prevent damage in case the bubbling oil spills.Handle the magnet with tongs due to temperature extremities.Allow magnet to reach thermal equilibrium ( which is why it is kept in a steady temp for some time) toensure uniform temperature distribution. Only then measure the flux density with hall probe.As stated above perform the experiment away from any magnetic material that might distort the values forflux density.


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Q1. A fine wire mesh has individual wires that are spaced very close together. See flg. 1.1.

Fig. 1.1

The mesh behaves like two diffraction gratings placed at right angles to each other. The diffractiongrating formula is dsin = n

The spacing between the wires of the mesh is to be found accurately. Design a laboratory experiment

using light of a single wavelength to determine the spacing between the wires. You may assume that thewavelength of the light is known.

You should draw a detailed labeled diagram showing the arrangement of your apparatus. In youraccount you should pay particular attention to

(a) the type of light source to be used, giving a reason for your choke, (b) the procedure to be followed and the measurements that would be taken, (c) how the measurements would be used to find values of 0,(d) how the spacing between the wires would be deduced,(e) any safety precautions you may take.


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Marking key:

Diagram of arrangement (light source/mesh/screen or collimator/mesh/telescope) [1]

Fringes or dots shown on screen. May be shown on diagram. [1]

Some sensible discussion of coherence [1]

Use of laser or single slit (and lens) in collimator [1]

Measurements: distance from mesh to screen and separation between fringesOR measure an angle from the spectrometer table [1]

n = 1; find separation between central fringe and first bright fringeOR measure angle between central bright beam and first order beam using scale on table [1]

Use of dsin = nto find d. n must be clearly identified [1]

Any safety precautione.g. use goggles/do not look directly into laser beam/cover over sodium lamp do not touch the bulb [1]

Any good/further detail [2]Examples of creditworthy points might be:Take readings with mesh in different positions to average dSketch/suggestion of two-dimensional array of dots on screenLaser + mesh 4- screen all at same heightX = 589 nm for sodium lamp or aboutK= 630 nm for He/Ne laser/semiconductor laserof the order of 1 m to 4 m (laser method)

Measure 20 and 4ivide by two to reduce uncertainty in 0

Repeat experiment with 2nd order (3rd order etc.) beamsDetail relating to setup/use of spectrometer

Allow other valid points.

[Total: 10 marks]Report:

In this question candidates were required to design a laboratory experiment to investigate how todetermine the spacing between wires of a fine mesh using light of a single wavelength.

It was expected that candidates would show a labelled diagram of the setup showing a light source, a wiremesh and a screen. It was expected that candidates would be able to identify a source giving

monochromatic light from a point source (e.g. laser, Sodium lamp plus slit to name a few possibilities).

Weak candidates used ultra-violet, infra-red, gamma, alpha, microwaves or 'white monochromaticlight'; Some candidates used a light bulb which when combined with a filter and a slit was credited.Many candidates responded with a double slit setup or used a diffraction grating instead of the wiremesh which was not credited. The best candidates realised that the pattern produced on the screenwould be a rectangular array of bright dots (candidates were not required to work this out). Answers thatreferred to crossed patterns of lines or to circular fringes were allowed. Weak candidates showed nopattern at all or made no reference to a pattern within the written text.


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It was expected that candidates would state the quantities they would measure in order to find 0. Manycandidates used a protractor without credit (indicating candidates did not appreciate the size of anglesinvolved). Good candidates said they would measure D, the mesh to screen distance, and x, the dotseparation. Good candidates took these measurements and used tan =x/D to find and subsequently useddsin = n (where n = 1) to find d. Weaker candidates confused the symbols and their meaning, forexample d, instead of being the 'spacing between the wires', became 'the distance between the mesh

and the screen. Also many candidates thought d= I/spacing. It was expected that n would be given a value(e.g. n = 1) in order to use the equation dsin = n . Vague comments about the 'order of a fringe' did notgain credit Some strong candidates labelled a spectrometer and gained marks for taking the angle from thetable and saying how they did this in detail. Some good candidates suggested plotting n , against sin to getdfrom the gradient.

A good well-annotated diagram could gain up to half marks for this question, whereas a poor oneoften received little or no credit

Sensible safety ideas only were given credit (e.g. 'do not look at the source directly' or 'use goggles toprevent damage to eyes'). 'Do not point laser at skin as it will burn' was not credited.

Marks were available for good further detail. Many candidates were able to access these marks. Nocredit was given for a darkened room as coherent light will produce visible fringes in a classroom.However, few candidates appreciated the need for a coherent source.

Cambridge International Examinations Paper 5

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