Investigation into the relationship between the length of a wire and the resistance
Investigation into the relationship between the length of
a wire and the resistance
Plan
Introduction
A metal conductor consists of atoms surrounded by a 'sea' of electrons; each atom donates electrons to the 'sea'. The electrons are always moving, but if there is no potential difference applied to either end, they move randomly. When a P.D. is applied the movement of the electrons is influenced and there is a net movement in a particular direction.
In doing so they lose energy by colliding with atoms; the atoms gain energy and vibrate more, decreasing the chance of an electron passing without colliding.
Preliminary Work
We measured the resistance of 32 and 40 standard wire gauge at 10cm intervals between 0 - 30cm.
Thickness of wire/ Standard Wire Gauge
Length/ Cm
Resistance/ ?
Resistance minus probes/ ?
32
0
0.1
0.0
0
1.3
1.2
20
2.2
2.1
30
4.1
3.0
40
0
0.1
0.0
0
5.1
5.0
20
9.1
9.0
30
2.7
2.6
The results show resistance increasing as wire length increases resistance increases.
Hypothesis
I therefore predict that as the wire length increases so will the resistance, as the electrons will have to pass more atoms increasing the chance of a collision and slowing the electrons down. Also as the thickness of wire increases the resistance will decrease, as there will be more electrons so the chance of an electron not colliding increases. This is what the preliminary work seemed to show.
Plan
* Set the apparatus up as show above. The masking tape hold the wire as taut as possible, so the wire does not have kinks or bends which make the wire appear shorter than it actually is.
* Connect two probes to a multi-metre and set it to measure ohms (the unit of resistance).
* First hold the probes together to measure the resistance in them this number can be subtracted from the results to leave the actual resistance of the wire.
* Place the first probe firmly on the 0cm mark of the metre rule. Place the second probe on every 10cm interval to the end of the rule in order to vary the length of the wire, e.g. 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100cm. (The probes must be held firmly to the wire to make a good contact or the resistance of the contact will throw off the results.)
a wire and the resistance
Plan
Introduction
A metal conductor consists of atoms surrounded by a 'sea' of electrons; each atom donates electrons to the 'sea'. The electrons are always moving, but if there is no potential difference applied to either end, they move randomly. When a P.D. is applied the movement of the electrons is influenced and there is a net movement in a particular direction.
In doing so they lose energy by colliding with atoms; the atoms gain energy and vibrate more, decreasing the chance of an electron passing without colliding.
Preliminary Work
We measured the resistance of 32 and 40 standard wire gauge at 10cm intervals between 0 - 30cm.
Thickness of wire/ Standard Wire Gauge
Length/ Cm
Resistance/ ?
Resistance minus probes/ ?
32
0
0.1
0.0
0
1.3
1.2
20
2.2
2.1
30
4.1
3.0
40
0
0.1
0.0
0
5.1
5.0
20
9.1
9.0
30
2.7
2.6
The results show resistance increasing as wire length increases resistance increases.
Hypothesis
I therefore predict that as the wire length increases so will the resistance, as the electrons will have to pass more atoms increasing the chance of a collision and slowing the electrons down. Also as the thickness of wire increases the resistance will decrease, as there will be more electrons so the chance of an electron not colliding increases. This is what the preliminary work seemed to show.
Plan
* Set the apparatus up as show above. The masking tape hold the wire as taut as possible, so the wire does not have kinks or bends which make the wire appear shorter than it actually is.
* Connect two probes to a multi-metre and set it to measure ohms (the unit of resistance).
* First hold the probes together to measure the resistance in them this number can be subtracted from the results to leave the actual resistance of the wire.
* Place the first probe firmly on the 0cm mark of the metre rule. Place the second probe on every 10cm interval to the end of the rule in order to vary the length of the wire, e.g. 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100cm. (The probes must be held firmly to the wire to make a good contact or the resistance of the contact will throw off the results.)
