Resistance of a Wire
The resistance of a wire
Planning:-
Introduction:
To investigate the resistance of a wire at different lengths to see whether or not a longer wire has a larger resistance than a shorter wire.
Apparatus:
Wire
Voltmeter
Ammeter
Battery
2 crocodile clips
Metre rule
Variable resistor
Diagram:
Variables:
Length
Thickness
Resistance
Material
The material and diameter of the wire needs to be kept constant to keep the test fair as we are investigating resistance. The independent variable will be the length of wire as we will be changing it to see whether or not the resistance changes. The dependent variable will be the resistance of the wire as that is what is going to change due to the length of wire.
The length of wire will be measured accurately using a metre rule. The wire will be stuck onto the rule using tape. This means that the wire will not move about so we can measure the length accurately. Repeating measurements improve accuracy as you can spot any anomalies and the results can be averaged to give more reliable results. The voltmeter will give the reading for voltage ( V ) and the ammeter will give the reading for current ( I ). The resistance will then be calculated using the formula R=V/I. A variable resistor will be used to give three sets of voltage and current readings so we can work out the resistance of the wire. These three values will be taken for each length of wire. Each value will have a resistance. These three resistances will be added together and then divided by three to give an average resistance.
Preliminary measurements:
These preliminary measurements are taken so we can choose the wire which gives a range of resistance values as the length is changed. A high resistance means less current so there is less chance for the wire to get hot. The maximum current must not cause the wire to get hot. This because it will give unreliable results because the resistance increases. Also, the use of preliminary
Planning:-
Introduction:
To investigate the resistance of a wire at different lengths to see whether or not a longer wire has a larger resistance than a shorter wire.
Apparatus:
Wire
Voltmeter
Ammeter
Battery
2 crocodile clips
Metre rule
Variable resistor
Diagram:
Variables:
Length
Thickness
Resistance
Material
The material and diameter of the wire needs to be kept constant to keep the test fair as we are investigating resistance. The independent variable will be the length of wire as we will be changing it to see whether or not the resistance changes. The dependent variable will be the resistance of the wire as that is what is going to change due to the length of wire.
The length of wire will be measured accurately using a metre rule. The wire will be stuck onto the rule using tape. This means that the wire will not move about so we can measure the length accurately. Repeating measurements improve accuracy as you can spot any anomalies and the results can be averaged to give more reliable results. The voltmeter will give the reading for voltage ( V ) and the ammeter will give the reading for current ( I ). The resistance will then be calculated using the formula R=V/I. A variable resistor will be used to give three sets of voltage and current readings so we can work out the resistance of the wire. These three values will be taken for each length of wire. Each value will have a resistance. These three resistances will be added together and then divided by three to give an average resistance.
Preliminary measurements:
These preliminary measurements are taken so we can choose the wire which gives a range of resistance values as the length is changed. A high resistance means less current so there is less chance for the wire to get hot. The maximum current must not cause the wire to get hot. This because it will give unreliable results because the resistance increases. Also, the use of preliminary