So i partenered up with a friend and made a disccusion with our physics teacher about what kind of practical we should investigate, we decided to see the impact that temperature and length of a would wire have on the resistence and therefore power loss. Our question for the investigation was 'How does temperature and length affect power loss in a DC circuit?' We knew that the current may effect the data but we assumed that it was constant and it wasn't going to have a major impact since we wont be connecting the wires to any power supply. We put a 5m wire (rolled) in a beaker above a hot plate with a thermometer measuring temp and ammeter connected to the wire to measure the resistence at different temperatures, we straight away found huge fluctuations in the resistence and they weren't consistent and made no logical sense, we couldn't do any testing with the length measurements and its impact on resitence (atm). Now after research we have realised that that the wires must be much longer to see any proper change in resistence that can be detected in a basic ammeter. We still have 100 minutes left of class time what can we do to get some sort of acceptable data that we can discuss? and what should we do in the discussion for this practical investigation (Unit 4 sac)??
Hey,
I made a list of something things you might be interested in talking about in your discussion:
- relationship between resistance-length, resistance-temperature and finally current-resistance.
-- Here you can mention the fact that there is a greater resistance when the length of the wire/ temperature of the surroundings is increased. I would suggest mentioning the theoretical aspects to begin with, and then moving on to your practical results (for which you can take the highest resistance value
only if you can see a trend, otherwise I would suggest taking the resistance values that occurred at the same time in each event).
- Since you are looking at power loss, mention the formula (Ploss = I^2 x R) and relate it the fact that increasing the temperature/ length of the wire increases Ploss as there would be a greater resistance.
- Talk about the uncertainties of your measuring material to talk about inaccuracies.
ie thermometer with plus or minus 0.05 Celsius (if it goes to one decimal place) and ruler with plus or minus 0.05 cm (If you are using a ruler that has mm on it), which may have led to outliers.
- Temperature not being constant at all times.
-- mention Maxwell-Boltzmann distribution to validate your inferences (about the errors) by arguing that all particles does not have the same kinetic energy.
- systematic errors (you have already mentioned a few for yourself)
-- You have already mentioned neglecting current, so you can talk about temperature (the fact that you can conducting the practical in an open system) and the fact that the wires had to be longer which may have results in inaccurate results.
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