Paper 1 - Investigating Resistance Flashcards
what are some of the things the resistance of a circuit depend on
2 points
1) whether the components are in series or parallel
2) the length of the wire
what equipment is used in this experiment
6 points
1) ammeter
2) voltmeter
3) circuit with switch and battery
4) crocodile clips
5) test wire
6) metre ruler
draw the circuit for this experiment
pg 42
what does the ammeter do and where must it be placed
2 points
1) measure the current flowing through the wire
2) must be placed in series
what does the voltmeter do and where must it be placed
2 points
1) measures the p.d across the test wire
2) must always be placed in parallel around whatever you’re investigating
what’s the method for this experiment
5 points
1) attach a crocodile clip to the wire level with 0cm on the ruler
2) attach a second clip to the wire e.g. 10cm away from the first and write down the length between clips
3) close the switch and record the current through the wire and pd across it
4) open the switch, move the second clip e.g. another 10cm down the wire, close the switch again and record new length, current and pd
5) repeat this for a number of different lengths
what should you do after the experiment
4 points
1) use your measurements of current and pd to calculate the resistance using R=V/I
2) then plot a graph of resistance against wire length and draw a line of best fit
3) the line should go straight through the origin and be directly proportional
4) if this doesn’t happen it could be a systematic error, like the first clip wasn’t exactly on 0cm so all your other measurements were slightly out
draw the graph for resistance against length of wire
pg 42
why should you keep the switch open in between each reading
2 points
1) the wire may heat up which would affects the resistance
2) leaving it open will let the circuit cool down
how should the wire be to give you the best results
2 points
1) thin
2) straight as possible
