- #1
cbs27
- 5
- 0
I have a piece of coursework due in soon (as a matter of fact, about 2 hours from now), and I need to know what the lmiting factors were. Here's the method:
(a copypasta from my handed-in plan)
For this experiment, I measured out a length of a resistive metal wire, and connected it to the circuit as shown above. I kept the wires that I used as short as possible, because even though they have very low resistance, they may affect my readings. Also, I connected the voltmeter as close as possible to the resistive wire in order to measure only the voltage across the resistive wire. I measured the thickness of the resistive wire using a micrometer; I took three readings at various points throughout the section of wire I used, and made an average in order to be more accurate, being careful not to squash it. I measured out 1m of the resistive wire using a metre rule, being careful to straighten out any kinks in the wire. I then attached it with crocodile clips to the circuit. I checked first of all to see if there was a 0 error on the ammeter or voltmeter, and then to see the lowest voltage at which I could get suitable readings in the interest of safety, and found I could obtain a result from 3v. I then passed this voltage through the resistive wire, and took-down readings from the ammeter and voltmeter; being careful to run the current for as little time as possible so that the temperature of the resistive wire did not increase a lot, disturbing my readings. I then switched it off and repeated the experiment from 100cm at 10cm intervals down to 10cm with 3 repeats for each length, and an average made of the three for increased reliability of data. I waited in between the tests long enought for the wire to cool down in order to minimise the change in temperature.
Using the data I could then work out the resistivity of the wire, using:
ρ = RA/L Where ρ = Resistivity
R = Resistance
A = Cross-sectional area of the wire
L = length of the wire
Thanks in advance for any help you may be able to give me!
Regards,
cbs27
(a copypasta from my handed-in plan)
For this experiment, I measured out a length of a resistive metal wire, and connected it to the circuit as shown above. I kept the wires that I used as short as possible, because even though they have very low resistance, they may affect my readings. Also, I connected the voltmeter as close as possible to the resistive wire in order to measure only the voltage across the resistive wire. I measured the thickness of the resistive wire using a micrometer; I took three readings at various points throughout the section of wire I used, and made an average in order to be more accurate, being careful not to squash it. I measured out 1m of the resistive wire using a metre rule, being careful to straighten out any kinks in the wire. I then attached it with crocodile clips to the circuit. I checked first of all to see if there was a 0 error on the ammeter or voltmeter, and then to see the lowest voltage at which I could get suitable readings in the interest of safety, and found I could obtain a result from 3v. I then passed this voltage through the resistive wire, and took-down readings from the ammeter and voltmeter; being careful to run the current for as little time as possible so that the temperature of the resistive wire did not increase a lot, disturbing my readings. I then switched it off and repeated the experiment from 100cm at 10cm intervals down to 10cm with 3 repeats for each length, and an average made of the three for increased reliability of data. I waited in between the tests long enought for the wire to cool down in order to minimise the change in temperature.
Using the data I could then work out the resistivity of the wire, using:
ρ = RA/L Where ρ = Resistivity
R = Resistance
A = Cross-sectional area of the wire
L = length of the wire
Thanks in advance for any help you may be able to give me!
Regards,
cbs27