Investigating the Factors that Affect the Resistance of a Wire

Investigating the Factors that Affect the Resistance of a Wire

Aim:

My aim is to find out how the length affects the resistance of a wire.

Safety:

§ I should not leave the power coming from the batteries on the wire

for too long as this will cause heating and might burn.

§ Be careful when touching the wire, as it may be hot.

§ I should just leave the batteries connected to the wire only for a

short time, as I only need to take a reading and take it off.

§ I should be careful when cutting the wire.

These few precautions will enable a very effective and safe

experiment, which will allow me to get good results without problems.

Ohms Law

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E = Electromotive force

(Volts)

I = Current

(Amps)

R = Resistance

(Ohms)

Ohms Law is defined as; "Provided that the temperature remains

constant, the ratio of potential difference (p.d.) across the ends of

a conductor (R) to the current (I) flowing in that conductor will also

be constant".

So from ohms law if we want an accurate result the temperature must

remain constant. Current equals Voltage divided by Resistance (I=V/R),

Resistance equals Voltage divided by Current (R=V/I), and Voltage

equals Current times Resistance (V=IR).

Factors of Wire

Thickness of a wire

-------------------

In theory a thicker wire offers less resistance. The resistance of a

wire is inversely proportional to its cross section width. If the

area/cross section of the of the wire is doubled, the resistance will

be halved. I will keep this the same by using the same roll of wire.

Length of a wire

----------------

If the length of a wire is doubled, the resistance is doubled. This is

because twice the length of wire is equivalent to two equal

resistances in series. This is going to be the factor that I will use,

so I will be changing the length while keeping the rest of the factors