The resistance of wire.

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Aim

I am going to be studying the resistance of wire. The purpose of this investigation is to see how length and thickness of wire affect the dependent variable, resistance.

Prediction

I predict that, as the length of the wire doubles, the resistance will also double, but as the cross-sectional area of the wire doubles, the resistance halves. This means that the length will affect the resistance more than the thickness will.

Hypothesis

Resistance is caused by electrons bumping into ions. If the length of the wire is doubled, the electrons bump into twice as many ions so there will be twice as much resistance. So

If the cross-sectional area of the wire doubles there will be twice as many ions and twice as many electrons bumping into them, but also twice as many electrons getting through twice as many gaps. If there are twice as many electrons getting through, as there is twice the current, the resistance must have halved. This means that essaybank.co.uk

I am assuming that the temperature is kept constant and that the material is kept constant. We can include this in our equations by adding a constant wweb ebw esebebs ayeb ebba neb kceb ebuk.

Method

Equipment needed:

1 x Power Pack (to give varied voltage)

1 x Voltmeter

1 x Ammeter

5 x wires (with crocodile clips)

wire of varied length and thickness

Controlled variables: wwfa faw esfafas ayfa faba nfa kcfa fauk!

Temperature (room temperature)

Wire material

Dependent variable:

Resistance

Independent variables:

Thickness of wire

Length of wire

Circuit diagram

First, set up the experiment as shown above. Turn on the power and set the power pack so that the voltmeter reads 0.1 volts. Take the reading from the ammeter recording both the current and the voltage. Then do exactly the same again but use voltages of 0.2 volts, 0.3 volts, 0.4 volts and 0.5 volts. This is so that when we work out the resistance (V/I) we will have five readings and can then take an average resistance. Then carry out the whole thing again, varying the length of the wire in intervals of 10cm from 10cm to 100cm. MuUSd6e Visit essaybank cf co cf uk cf for more cf Do not cf redistribute MuUSd6e

To do the thickness experiment, set up the equipment again as shown. Turn on the power and set the power pack to read 0.2 volts. Take the current reading then turn off the power and start again. Take four readings like this so that an average resistance can be found. Next, change the thickness of the wire and do the experiment again. Use the diameters 0.71mm, 0.56mm, 0.28 mm and 0.20mm. Although the diameters haven't the same interval between them, once we have worked out the resistance, we can draw a graph to discover any relationship between the thickness and the resistance of wire. wwfa faw esfafas ayfa faba nfa kcfa fauk; wwcd cdw escdcds aycd cdba ncd kccd cduk.

The equation for resistance = V/I

Results

SWG

(thickness/mm) Voltage/volts Current/amps V/I=R/ohms Average R/ohms

 

Thickness investigation (Length kept constant at 15cms)

Graph 1 - relationship between the wire's thickness and its resistance wwff ffw esffffs ayff ffba nff kcff ffuk.

Length/cm Voltage/volts Current/amps V/I=R/ohms Average R/ohms

Length investigation (Thickness kept constant at SWG24)

Graph 2 - relationship between the wire's length and its resistance

After doing the two graphs I have decided to do a graph of 1/thickness2, to see if thickness is inversely proportional to resistance.

Thickness/mm 1/Thickness2 Average resistance/ohms

 

Investigating thickness2 and resistance

Graph 3 - relationship between the wire's thickness2 and its resistance

Conclusion

I conclude that, as the length of a wire doubles, the resistance also doubles (provided the thickness of the wire is kept constant). I also conclude that, as the cross-sectional area of the wire doubles, the resistance halves (provided the length of the wire stays constant). I can conclude this because my graph shows that resistance is inversely proportional to 1/(thickness2). So 5OOpECo from 5OOpECo essay 5OOpECo bank 5OOpECo co 5OOpECo uk wwbg bgw esbgbgs aybg bgba nbg kcbg bguk!

The theory behind these conclusions are:

As the length doubles the resistance doubles. Resistance is caused by electrons bumping into ions. If the length of the wire doubles, the electrons bump into the ions twice as much so the resistance will double.

The four factors that affect the resistance of a piece of wire:

Length,

Diameter or thickness,

Temperature and

The type of metal.

From thinking about how I would do this investigation and the outcome of it, I decided to use the length of the wire as the variable.

Aim

The aim of my investigation is to investigate how length affects the resistance of a length of wire

Resistance is the force, which opposes the flow of an electric current around a circuit so that energy is required to push the charged particles around the circuit. Resistance is measured in ohms. A resistor has the resistance of one ohm if a voltage of one volt is requires to push the current of one amp through it.

Resistance occurs when the electrons travelling along the wire collide with the atoms of the wire.

These collisions slow down the flow of electrons causing resistance. Resistance is a measure of how hard it is to move the electrons through the wire.

Wire length: If the length of the wire is increased then the resistance will also increase as the electrons will have a longer distance to travel and so more collisions will occur. Due to this, the length increase should be directly proportional to the resistance increase.

To measure and record the results for this factor is simple, the results would be collected and could show a connection between the length of the wire and the resistance given by the wire. This is why I have chosen to investigate how resistance changes with length.

Ohms law, V=I/R. This says that for a certain current (charge flowing at a certain rate), there will be a greater voltage across the wire if it has more resistance. essaybank.co.uk

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This tells me that the voltage measures the amount of energy used up in getting each coulomb of charge through the wire. The units of volts are the same as joules per coulomb. Therefore, Ohms law says the more resistance means more energy used to pass through the wire. Resistance is a measure of how much energy is needed to push the current through something. The electrons carrying the charge are trying to move through the wire, but the wire is full of atoms that keep colliding in the way and making the electrons use more energy.

Preliminary Method

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