Investigating the Relationship Between Length and Resistance of a Wire

Investigating the Relationship Between Length and Resistance of a Wire

Aim

===

To investigate the effect the length of wire has on resistance.

Background information

======================

Ohm's Law. The current in an object at constant temperature is

proportional to the potential difference across its ends. The ratio of

the potential difference to the current is the resistance of the

object. The object must be at a constant temperature for the law to

apply since a current will heat it up and this will change its

resistance. [IMAGE]

(The Usborne Illustrated Dictionary of Science, C. Stockley, C.

Oxlade, J. Wertheim, Page 62)

Resistance (R). The ability of an object to resist the flow of

current. The value depends on the resistivity of the substance from

which the object is made and its shape. The unit of resistance is the

ohm (Ω). Electrons moving in the object hit atoms and give them

energy, heating the object and using up energy from the source of

electromotive force.

(The Usborne Illustrated Dictionary of Science, C. Stockley, C.

Oxlade, J. Wertheim, Page 62)

Preliminary Work

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Applied Voltage

Did wire get hot? ([IMAGE]/X)

0

X

2

X

4

X

6

[IMAGE]

8

[IMAGE]

Thickness (SWG)

Did power pack trip? ([IMAGE]/X)

Did wire get hot? ([IMAGE]/X)

26

X

X

30

X

X

32

X

[IMAGE]

From this I can tell I can use 3 volts and resistance wire that is

30SWG.

Prediction

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I predict that the longer the wire the more resistance it will have as

there are more atoms for the electrons to hit. [IMAGE]This will create

more heat making the atoms move about more increasing the resistance.

Thickness of the wire will have an effect. Thin wire is created by

rolling out a thicker peace there is less space between atoms for the