Practical Feedback

```Practical Feedback
5th December 2016
PAGs
• If the PAG sheet says “This practical activity is intended to
be carried out as an investigation in which you plan and
implement work to demonstrate your investigative skills”
• What do you think you should do?
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If it says “Determine a strategy to enable you to …..
“Obtain and record results”
“Caculate a value and evaluate your findings”
• Recording
• As evidence for the Practical Endorsement you should have
detailed your method and the variables which you took into
account. You should have evidence of the data collected in
a clear and logical format. All work should be clearly
dated.
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• In addition, in preparation for the assessment of practical
work in the written exam you should record your
calculations and an analysis and evaluation of your results.
Date
• All work must be dated.
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Shm 13/10/16
Shc of metal 16/11/16
Shc of liquid 24/11/16
Specific latent heat of fusion 28/11/16
Specific latent heat of vaporisation 1/12/16
• Shm and shc are looking for an INVESTIGATION.
• So you need to explain carefully, what you are measuring,
why, how and what your results and calculations show.
This is long.
Diagrams
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Large (half a page minimum)
Drawn in pencil – with a ruler
Labelled
No lines crossing over e.g Voltmeters with a wire through
or glassware with lines blocking the flow of water.
• Draw thermometers carefully.
Results Table
• Each column must contain a PHYSICAL QUANTITY and
a UNIT.
• Significant figures are dictated by the precision of the
instrument. (SF should be consistent across the table.
Mutiplying a 3 sf with a 2 sf will give an intermediary
answer of 3sf (2sf with an additional sf) however, if it is the
final answer quoted in the conclusion, it must be to 2sf (i.e
as accurate as the least precise bit of data).
• Decimal places should be consistent going down a column
Graphs
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Graphs must be drawn in pencil.
Scales have labels and UNITS
Graph has a title
Cut graph paper down so that it fits into the book.
Plotted points must cover AT LEAST HALF THE PAPER
IN BOTH THE X AND Y DIRECTIONS
• Gradients must be calculated using over half the line.
Calculations
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Show gradient calculation in the text – not on the graph.
DON’T FORGET THE UNITS
Explain the Physics. What is the gradient?
Why are you measuring it? What does it equate to.
Analysis
• Explain what you have found out. Write sensible ideas e.g “the probe
must have touched the heater as the water heated more easily than we
would expect”. Or “the water was not stirred sufficiently so only
heated a small amount of water around the probe, rather than heating
all the water.”
• Do not write “I don’t think we did this very accurately.” You have to
explain what was wrong with your experimental technique.
• Uncertainties. Calculate the uncertainty of the smallest data you have,
this will show the largest uncertainty. You do not need to calculate
each one.
• You are looking for your calculated uncertainty to be larger than the
percentage difference, then you can say that your experiment is valid
and you have an accurate value.
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