Constantan and Nichrome

If the length of the wire is doubled, the electrons bump into twice as many ions so there will be twice as much resistance. I’m going to summary my prediction to make it very clear. Longer the wire the more resistance the material has to electrical current compared to the short wire. This is so because the longer the wire, means more material and particles are included in the face of electrical current which has to struggle more to overcome these particles.

Variables The key variables in my experiment include the three materials (Copper, Nichrome and Constantan, length of wire, and diameter (or thickness) of wire.

First I will investigate the effect of material on resistance by measuring the resistance of the three materials while keeping the length of wire (10cm) and diameter of the wire (30cm) the same. This will allow me to see which material offers the highest and lowest resistance. From my experiment set-up I shall read the voltage and current using the voltmeter and ammeter, respectively.

From these readings I can calculate the respective resistance of each material. . In this experiment I will be observing and repeating this experiment 3 times to give a much more accurate set of results.

Secondly I shall vary the length of the wire while keeping the diameter of wire (30 cm) and type of wire as fixed variables, in order to investigate the effect of wire length on the resistance. Again I shall measure the voltage and current using the voltmeter and ammeter, respectively to allow me to calculate the wire resistance at various wire lengths.

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The range of wire length I am going to investigate varies from 10 cm to 100 cm. This allows me to have a fair test on the effect of wire length on resistance. Also In this experiment I will be observing and repeating this experiment 3 times to give a much more accurate set of results.

I will take the average of the three measurements for each material in order to get reliable results to calculate the resistance. Since there are three materials there will be nine measurements for voltage and current. Fair Test To make my experiment a fair test I will need to keep certain variables the same, and in this experiment, the effect of material on resistance, I will keep the following variables the same. Constant variables  Length of wire the same (10cm)  The diameter of the wire (30cm)  Temperature Current The importance of keeping the variable the same is vital, because it might effect our results.

Also I’m going to explain whys its important to keep this variables and explain how this would effect my set of results Temperature We must keep the surrounding room temperature the same or the particles in the wire will move faster (if the temperature is increased) and this will therefore have an effect on the resistance. Length of wire the same I must keep the length of the wire the same because As the length of the wire is increased the number of collisions the current carrying charged particles make with fixed particles also increases and therefore the value for the resistance of the wire becomes higher, and effect our results.

Material of wire The material of the wire must also be kept the same as different materials have different conductivity and this will therefore have an effect on the resistance, which might effect our results. Current The current that we pass through the wire is to be kept the same, also. If this is changed the temperature of the wire might change in a way that is not constant making the results more difficult and confusing, which might affect my results Experiment 2.

In my second experiment, to make it a fair test, is by keeping the length of the wire the same. Also I’m going to explain whys its important to keep this variables and explain how this would effect my set of results. Constant Variables  Temperature  The diameter the same   Current Temperature We must keep the surrounding room temperature the same or the particles in the wire will move faster (if the temperature is increased) and this will therefore have an effect on the resistance. The Diameter The Same.

We must keep the diameter the same because it will affect the resistance because the wider a wire the more space in the net for the charged electrons to get through without colliding with the net and therefore decreasing the resistance and effects our results. Material of wire The material of the wire must also be kept the same as different materials have different conductivity and this will therefore have an effect on the resistance, which might effect our results. Current The current that we pass through the wire is to be kept the same, also.

If this is changed the temperature of the wire might change in a way that is not constant making the results more difficult and confusing, which might affect my results. Method Firstly, I will collect together the following equipment such as Ammeter, Batteries, Wires and voltage. Next step is to connect all the equipment together to produce a circuit, like the one shown below. Then I will record my readings on the different types of materials (Copper, Constantan and Nichrome) to see the effect of each type of material on the resistance. I will then repeat each experiment 3 times.

Finally when I have repeated the process three times, then soon I will want to compare it to see if it was equal to the first experiment. This is how I will collect my results; place different material in the circuit and the record the results (current and voltage). I will take 3 numbers of readings. In the other Experiment – First thing that I’m going to do is to find a suitable metre ruler which match’s my requirements and then place a length of wire over a metre long and sellotaped it to a metre rule. Then I’m going clip a crocodile clip at the reading, which say 0cm.

And then attached another crocodile clip which moves up and down the wire, stopping at 10,20,30,40,50, 60, 80, 90 and 100cm. In this experiment I’m going to read the voltage and the current from its ammeter and voltage meter very carefully, this is because it will allow me to calculate the resistance of each length, Each time reading the ammeter and voltmeter to work out resistance R = V/I. Ranges of numbers and readings The range of wire length I am going to investigate varies from 10 cm to 100 cm. This allows me to have a fair test on the effect of wire length on resistance.

Also In this experiment I will be observing and repeating this experiment 3 times to give a much more accurate set of results. I will take the average of the three measurements for each material in order to get reliable results to calculate the resistance. Since there are three materials there will be nine measurements for voltage and current. Accuracy To keep this experiment as accurate as possible we need to make sure, firstly, that the length of the wire is measured precisely from the inside edge of the crocodile clips, making sure that the wire is straight when we do this.

We must also make sure that the wire is straight when we conduct the experiment. If it is not, short circuits may occur and bends in the wire may effect the resistance, also. The reading that we take of the voltage should be done fairly promptly after the circuit is connected. This is because as soon as a current is put through the wire it will get hotter and we want to test it when heat is effecting it the least, Analysis The way I calculated the resistance on each materials (Copper, Constantan and Nichrome) and on the length of wire was by using Ohm’s law, which is given as:

Table 2: Resistance of three Materials at fixed length and diameter First Try Material Voltage (v) Current (I) Resistance () Constantan 10 4. 5 2. 2 Copper 3. 2 5 0. 64 Nichrome 10 3. 8 2. 6 Second Try Material Voltage (v) Current (I) Resistance () Constantan 10. 1 4. 4 2. 3 Copper 3. 2 5 0. 64 Nichrome 10 3. 9 2. 6 Third Try Material Voltage (v) Current (I) Resistance () Constantan 10 4. 5 2. 2 Copper 3. 1 5 0. 62 Nichrome 10 3. 8 2. 6 Material Graph A Table 3: Effect of wire Length on resistance at fixed diameter and material First Try Length of wire (cm) Current(I).