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Any list of rules of log applicable in the Paper 5 ?
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Physics Paper 5 tips
- Thread starter arlery
- Start date
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You are welcome.Thanks so much!
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hi
The worst fit line is the line u draw after drawing the error bars
draw the line from the highest error bar of the first point to the lowest error bar of the final point
how it helped
thank u sooooo much..!! Allah bless u..
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can any1 guide me how to calculate absolute errors in gradient and y intercept? alsoow to how to draw worst fit line in graph? plzz
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Hey I just wanted to ask if it's okay to write the process in question 1 in bullet point form, under the specific headings. I won't get penalised for that right?
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error in gradient= gradient of best fit line - gradient of worst acceptable line
error in y-intercept= y-intercept of best fit line - y-intercept of worst acceptable line
for drawing worst acceptable line check out the previous post u just have to draw the line from highest error bar of first point to lowest error bar of last point
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thaanks ramsha , can u post pic of similar ques?
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Ramsha007 tel me how to do quest 2 part c in http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s09_qp_5.pdf
The syllabus states recognize and use the logarithmic forms of expressions like ab, a/b, x^n, e^kx and understand
the use of logarithms in relation to quantities with values that range over several orders of
magnitude.
Paper 5 Tips: Practical Test
Planning Question
• Do not panic if the context of the question appears unfamiliar to you. During your A Level studies you will have used or learnt about suitable apparatus for completing the task. If you are asked to ‘use’ any unfamiliar apparatus the question will supply you with all the details that you need to know about.
• Read the question very carefully – it may give you guidance on those aspects of your plan to which you need to pay particular attention. It will also help you to identify the independent and the dependent variables.
• When writing your answer you will need to consider some or all of the following:
- what apparatus you will use
- what experimental arrangement will be used
- what procedure will be followed
- the independent and dependent variables
- the means of keeping other variables constant - use the word ‘constant’
when identifying these variables, saying you will ‘control’ them is insufficient
- how the raw data readings will be processed to give the desired result, e.g. what derived quantities you might calculate or what graph you might plot
- what relevant safety precautions should be in place
• The relationship to be tested, given to you in the introduction to the task, will
suggest the type of graph to be expected. You will need to describe it as
precisely as possible. For example, is it linear, does it pass through the origin? If
you choose a logarithmic graph, you will be expected to predict its slope from the
given expression.
• When writing your answer you must write down all the information clearly and
explicitly - the examiner cannot give you marks for things that are vaguely implied.
• Many of the marks can often be scored by having a good working diagram (even if the accompanying explanation is weak) and so you should spend time making sure that your diagram shows all the relevant details and is fully labelled. For example, make clear the exact points, between which, measurements, such as distance, are to be made.
• The equipment and procedures that you describe in your answer should be realistic and workable.
• One mark is available for describing safe working. This must relate specifically to the apparatus being used. It is not sufficient to write, for example, ‘keep all bags and coats out of the way’.
• Additional marks are available for detailed descriptions of apparatus/techniques. There are always more possible answers than marks available, so if you write your plan carefully, then some these marks should be gained as you go along. It is not expected that you write a separate section solely for the detail marks.
• As part of your preparation for this question you should plan some of your own experiments, but this should be done under the close supervision of your teacher. Also practise answering past papers.
• A sketch graph is not necessary, but if drawn it should be consistent with your description of the graph.
Evaluating data Question
• The number of significant figures used in a derived quantity that you calculate from your raw readings should be equal in number to (or possibly one more than) the number of significant figures in the raw readings. For example, if you measure potential difference and current to 2 and 3 sig figs respectively, then the corresponding value of resistance calculated from them should be given to 2 or 3 sig figs, but not 1 or 4. If both were measured to 3 significant figures, then the resistance could be given to 3 (or 4) sig figs.
• When drawing your graph, do not forget to label each axis with the appropriate quantity and unit, using the same format for expressing column headings in a table. Choose a scale such that the plotted points occupy at least half the graph grid in both the x and y directions. The x-axis scale should increase positively to the right and the y-axis scale should increase positively upwards. Use a convenient scale such as 1, 2 or 5 units to a 2cm square as you will then be less likely to make a mistake with the position of your plotted points and it will be easier for you to read off points from your graph if you are calculating the gradient or finding an intercept. Similarly, it is good practice to mark values on at least every other 2cm square.
• All your plotted points should be on the grid; points in the white margin area will be ignored. Plot all your observations and ensure that they are accurate to half a small square. A fine cross (or an encircled dot) drawn with a sharp pencil is acceptable, but be careful not to obscure the position of your points by your line of best fit or other working.
• When drawing your line of best fit, ensure you have an even balance of points about the line along its whole length. If it is a straight line, use a clear plastic rule so that you can see points on both sides of the line as it is being drawn.
• Show all your working when calculating a gradient. It is helpful to draw the triangle used to calculate the gradient on the graph and to clearly label the coordinates of the vertices (accurate to half a small square). These values can then be used in the gradient calculation. The length of the hypotenuse of the triangle should be greater than half the length of the graph line.
• If you are required to give a value for the y-intercept, it may be possible to directly read it off from your graph from an axis where x=0. If this is not possible you can instead calculate the y-intercept by using the equation of a straight line. In this case you should substitute into this equation a pair of x and y values from your line of best fit along with your calculated value of gradient.
• It is particularly important that the rules, previously given for significant figures, are strictly adhered to.
• You will be expected to use the uncertainty given in the raw data to find the uncertainty in calculated data. The latter will involve a function such as a logarithm. This requires plenty of practise, if you are to be able do it with confidence in the examination.
• You will need to be able to translate the calculated uncertainties into error bars on your graph and then to draw the worst acceptable line. Again, this requires plenty of practise.
• Once the graph has been drawn, you will be expected to find uncertainties in both the gradient and the intercept – using your line of best fit and your worst acceptable line. A lot of marks depend on your being able to calculate the uncertainties in the calculated data.
• Every candidate is provided with the same data and so the final values calculated should be very similar. One mark is available to candidates who manage to work within a given tolerance, determined by the Principal Examiner.
Source:Learner Guide for Cambridge AS and A Level Physics(© Cambridge International Examinations 2012)
Hope this helps!!!
Planning Question
• Do not panic if the context of the question appears unfamiliar to you. During your A Level studies you will have used or learnt about suitable apparatus for completing the task. If you are asked to ‘use’ any unfamiliar apparatus the question will supply you with all the details that you need to know about.
• Read the question very carefully – it may give you guidance on those aspects of your plan to which you need to pay particular attention. It will also help you to identify the independent and the dependent variables.
• When writing your answer you will need to consider some or all of the following:
- what apparatus you will use
- what experimental arrangement will be used
- what procedure will be followed
- the independent and dependent variables
- the means of keeping other variables constant - use the word ‘constant’
when identifying these variables, saying you will ‘control’ them is insufficient
- how the raw data readings will be processed to give the desired result, e.g. what derived quantities you might calculate or what graph you might plot
- what relevant safety precautions should be in place
• The relationship to be tested, given to you in the introduction to the task, will
suggest the type of graph to be expected. You will need to describe it as
precisely as possible. For example, is it linear, does it pass through the origin? If
you choose a logarithmic graph, you will be expected to predict its slope from the
given expression.
• When writing your answer you must write down all the information clearly and
explicitly - the examiner cannot give you marks for things that are vaguely implied.
• Many of the marks can often be scored by having a good working diagram (even if the accompanying explanation is weak) and so you should spend time making sure that your diagram shows all the relevant details and is fully labelled. For example, make clear the exact points, between which, measurements, such as distance, are to be made.
• The equipment and procedures that you describe in your answer should be realistic and workable.
• One mark is available for describing safe working. This must relate specifically to the apparatus being used. It is not sufficient to write, for example, ‘keep all bags and coats out of the way’.
• Additional marks are available for detailed descriptions of apparatus/techniques. There are always more possible answers than marks available, so if you write your plan carefully, then some these marks should be gained as you go along. It is not expected that you write a separate section solely for the detail marks.
• As part of your preparation for this question you should plan some of your own experiments, but this should be done under the close supervision of your teacher. Also practise answering past papers.
• A sketch graph is not necessary, but if drawn it should be consistent with your description of the graph.
Evaluating data Question
• The number of significant figures used in a derived quantity that you calculate from your raw readings should be equal in number to (or possibly one more than) the number of significant figures in the raw readings. For example, if you measure potential difference and current to 2 and 3 sig figs respectively, then the corresponding value of resistance calculated from them should be given to 2 or 3 sig figs, but not 1 or 4. If both were measured to 3 significant figures, then the resistance could be given to 3 (or 4) sig figs.
• When drawing your graph, do not forget to label each axis with the appropriate quantity and unit, using the same format for expressing column headings in a table. Choose a scale such that the plotted points occupy at least half the graph grid in both the x and y directions. The x-axis scale should increase positively to the right and the y-axis scale should increase positively upwards. Use a convenient scale such as 1, 2 or 5 units to a 2cm square as you will then be less likely to make a mistake with the position of your plotted points and it will be easier for you to read off points from your graph if you are calculating the gradient or finding an intercept. Similarly, it is good practice to mark values on at least every other 2cm square.
• All your plotted points should be on the grid; points in the white margin area will be ignored. Plot all your observations and ensure that they are accurate to half a small square. A fine cross (or an encircled dot) drawn with a sharp pencil is acceptable, but be careful not to obscure the position of your points by your line of best fit or other working.
• When drawing your line of best fit, ensure you have an even balance of points about the line along its whole length. If it is a straight line, use a clear plastic rule so that you can see points on both sides of the line as it is being drawn.
• Show all your working when calculating a gradient. It is helpful to draw the triangle used to calculate the gradient on the graph and to clearly label the coordinates of the vertices (accurate to half a small square). These values can then be used in the gradient calculation. The length of the hypotenuse of the triangle should be greater than half the length of the graph line.
• If you are required to give a value for the y-intercept, it may be possible to directly read it off from your graph from an axis where x=0. If this is not possible you can instead calculate the y-intercept by using the equation of a straight line. In this case you should substitute into this equation a pair of x and y values from your line of best fit along with your calculated value of gradient.
• It is particularly important that the rules, previously given for significant figures, are strictly adhered to.
• You will be expected to use the uncertainty given in the raw data to find the uncertainty in calculated data. The latter will involve a function such as a logarithm. This requires plenty of practise, if you are to be able do it with confidence in the examination.
• You will need to be able to translate the calculated uncertainties into error bars on your graph and then to draw the worst acceptable line. Again, this requires plenty of practise.
• Once the graph has been drawn, you will be expected to find uncertainties in both the gradient and the intercept – using your line of best fit and your worst acceptable line. A lot of marks depend on your being able to calculate the uncertainties in the calculated data.
• Every candidate is provided with the same data and so the final values calculated should be very similar. One mark is available to candidates who manage to work within a given tolerance, determined by the Principal Examiner.
Source:Learner Guide for Cambridge AS and A Level Physics(© Cambridge International Examinations 2012)
Hope this helps!!!
- calculate the gradient of best fit line
- calculate the gradient of worst fit line
- error=worst gradient-best gradient (BECAUSE OTHERWISE THE CHANGE IS NEGATIVE)
Hope this helps
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The third step is only done if the answer of error in (gradient= gradient of best fit line - gradient of worst acceptable line) is negative so u can decide which one to use on the bases of seeing which value is bigger because u need a positiveerror value
- calculate the gradient of best fit line
- calculate the gradient of worst fit line
- error=worst gradient-best gradient (BECAUSE OTHERWISE THE CHANGE IS NEGATIVE)
Hope this helps
U getting negative answer from best gradient-worst gradient in this question
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,....Error can both be either positive or negative..so it does not matter whether u get positive or negative error because gradient(+_)error...The third step is only done if the answer of error in (gradient= gradient of best fit line - gradient of worst acceptable line) is negative so u can decide which one to use on the bases of seeing which value is bigger because u need a positive error value
- calculate the gradient of best fit line
- calculate the gradient of worst fit line
- error=worst gradient-best gradient (BECAUSE OTHERWISE THE CHANGE IS NEGATIVE)
Hope this helps
U are correct although it is said to calculate the gradient error this way in the marking scheme to get positive answer.May be the examiner recommends this or something
So u do the other way round and the negative sign goes away.U getting negative answer from best gradient-worst gradient in this question
Read my comment #9
https://www.xtremepapers.com/community/threads/physics-paper-5-notes.27194/#post-585614
And to join them u need to draw a straight line from the the bottom of the first error bar to the top of the last error bar and make sure your line passes through all the error bars.