Investigating Factors Affecting Resistance of a Wire


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Investigating Factors Affecting Resistance of a Wire

Aim
---

Investigate what factors affect the resistance of wire, however in
this experiment I am going to monitor how the length of a wire affects
the resistance of a wire if the current is kept the same.


Method
------

1) Arrange apparatus as shown in the Diagram:

2) Cut a length of wire over a meter long and sellotape to a meter
ruler.

3) Attach one positive crocodile clip to 0cm, and move the negative
up/down, stopping at;

5cm

10 cm

15 cm

20 cm

25 cm

30 cm

4) Attach the wire to the crocodile-clip leads and set voltage to 1

5) Other variables such as voltage, diameter of wire and
temperature will be kept constant.

6) Take the reading from the ammeter and record in results table.
(trying to keep the volt reading the same at all times, adjusts using
the variable resistor)

5) Repeat 3 times for each length of wire and find the average.

6) Then work out the resistance using the formula V÷I=R

(Voltage ÷ Current = Resistance)

Apparatus

Power Pack

Constantan wire

Leads

Voltmeter

Ammeter

Crocodile clips

1-meter ruler

Variable resistor

Fair test:

To make this fair test I kept some of the things constant. Variables
kept constant are the temperature (did experiment on the same day),
thickness/diameter 32 standard weight gage (swg), use same type of
material (nichrome), current (using variable resistor).

There was one thing I had to change during the experiment; this was
the length of the wire. Temperature has an affect on the experiment as
the voltage has control over the temperature. The more the temperature
increases the more the particles vibrate leading to a reduction in
output voltage although not by a huge amount this does have an affect.

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MLA Citation:
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Current will be kept constant by reostat. The type of material used
will make a difference because the electrons have to pass through the
material. These electrons find it easier to pass through some
materials the others. The more electrons ‘bump’ together higher the
resistance.

Density has a large affect on the amount of resistance. The resistance
depends upon the amount of denseness e.g. a large surface area has
less resistance because a small area has tightly packed atoms which in
turn rebound many of these electrons.

Safety

Due care and attention, wire can be hot if voltage is high

Prediction

I think as you increase the length of the wire, you also increase the
amount of resistance. The current is the flow of electrons; the
current is dependent on the amount of voltage, which is applied.
Voltage is the push given to the current. The current has to go
through a circuit, which contains resistance so if you increase that
push you also increase the flow of the current. All materials have a
slight resistance to electricity factors affecting the resistance are:
Length, Voltage & Temperature and Surface Area

The lengths I was going to use were

5cm

10 cm

15 cm

20 cm

25 cm

30 cm

35 cm

for the main experiment. And to see if my prediction is still correct
if I increase the range of lengths of wire used I am going to use
these lengths as well

10 cm

20 cm

30 cm

40 cm

50 cm

60 cm

wire was very weak if given more than 5 volts because the wire lets
electricity flow faster and faster which then leads to the heat
eventually breaking the wire. I found that if I decreased the voltage
to a reading of 1 volt the wire stayed in tact enough to give a good
reading and thereby giving better overall results.

Preliminary Experiment

We carried out a preliminary experiment to see the other factors that
could affect the experiment and also to see if we could improve any of
the steps in the method. This showed that the wire was very weak if
given more than 5 volts because the wire lets electricity flow faster
and faster which then leads to the heat eventually breaking the wire.
I found that if I decreased the voltage to a reading of 1 volt the
wire stayed in tact enough to give a good reading and thereby giving
better overall results.


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