Relationship between the current and voltage

... the luxmetre into the cardboard box, ensuring that its sensor is very close to the bulb each time round and that it is pointing towards the bulb. 3) Turn the lux meter on, and record the % it shows. * Deduct this from the results you receive once, the circuit is in use.

4) Turn the potentiometer to the maximum, so that you can find out what the maximum pd. will be from this you can derive a suitable scale to go up in, so that you can acquire sufficient results to plot a graph.

5) On the desired scale, carry out the experiment, recording the voltage, and current. Do this until you have acquired suitable results to plot a graph.

6) Once you have completed the experiment once, repeat the experiment 2 more times, so that an average can be calculated.

Analysis:

For the wire-wound resistors, which were 1 ohm and 2-ohm resistors, the results proved a directly proportional relationship between the pd. and current, of the circuit. This was due to the fact of the resistance being kept constant, through out the readings. The graph for these were a straight line, with positive gradients which proved my prediction to be correct, see graph one (1 Ohm resistor) and graph two (2 Ohm resistor). This means that ohms law was applicable in this experiment. From fig 1, it is evident, that ohms law is applicable. This is demonstrated by all the points lying on the best-fit line. The resistance, was first calculated by using ohms law, of V=IR, which was rearranged to R=V/I. As seen on the table of results, for 1 ohm resistor, the resistance received by using the formula, was 1.11 ohms. This is very close to 1 ohm, which was resistance of the resistor used. This provided sufficient evidence, to believe that the results I received were correct. By drawing a (V, I) graph, the resistance again can be derived, and be seen whether it matches the figure calculated using ohms law. The resistance was calculated, by using the gradient of the graph. This is because:

Y = m x X + c

V = R x X + 0 The resistance calculated, for the 1-ohm resistor, is slightly higher than the 1 Ohm, by 0.11 Ohms it ...