voltmeter variable resistor The apparatus was set up as shown on the diagram. 20cm of putty was fixed between P and Q, with a one-penny coin at both ends, using crocodile clips. An asbestos mat was placed underneath the wire for safety. The current flowing through the wire was recorded to the nearest 0.01A using an ammeter placed in series, in the circuit. The voltage across the wire was measured to the nearest 0.01V using a voltmeter placed in parallel, across the wire.The cell terminals were then reserved so that the current would flow in the opposite direction and the readings of V and I, were again taken, then recorded to give repeat readings.The 2 readings for current or I were averaged, and the 2 readings for V or voltage were averaged.The resistance was the calculated using the formula; R=V / IThe length of the putty was recorded. The putty was 20cm to start off with, and 2cm were then cut off after each reading. The experiment was repeated 10 times. Each time 2cm was cut off, the current through the wire and the voltage across the wire changed. The new readings of the current and voltage were taken, repeated the averaged as before, and R was calculated.As mentioned before, the experiment was repeated 10 times altogether, shorting the wire 2cm each time, to give a range of 20cm to 2cm.Before I carried out my experiment, I first carried out a preliminary experiment.Here are my results for my preliminary experiment:Length of putty in cm:20cm10cm2cmCurrent (I) to 0.01A:0.090.170.45Voltage (V) to 0.01V:3.312.762.09Resistance (0.01Ω)36.7816.244.64I found out that the experiment did work, no changes need to be made and also my prediction so far is correct because the longer the length of putty is, the bigger the resistance.For example,20cm = 36.782cm = 4.64 Analysis: Looking at my gr...
