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? • • • • If it says “Determine a strategy to enable you to ….. “Detail your plan” “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. • • 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. • • • • • 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 • • • • 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 • • • • • 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 • • • • 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.