Physics help plz?

Question

in a yr 10 experiment called how does resistance change along a wire, i need to know why you vary the amount of voltage in the experiment. Thanx

Answer 1

To make the experiment more reliable by providing a variety of readings.

Answer 2

The resistance increases proportional to temperature.

The resistance is opposite proportional to the cross area of the wire.

Each wire material has a specific Resistance pr mm^2 cross area each meter length.

Answer 3

You need to vary the voltage so you can get a variety of readings which will allow you to plot a graph. The gradient of this graph will tell you how much resistance increases as the wire gets longer.

Set up a simple test circuit and use a variable resistior between the power supply and the ammeter and vary its resistance to alter the voltage.

Answer 4

Well Tobes I guess you weren't paying attention in class were you.

I presume you are investigating the change in current in a circuit as the length of the wire is changed.

Connect up a circuit with a power source, ammeter and a length of wire in series. The wire is connected via a croc clip that can be clipped on the wire at various lengths. A voltmeter could be placed in parallel across the length of wire if required - this can be used to  give an actual resistance value.

Decide on what lengths of wire you are to investigate - 10, 20, 30, cm .......etc.

Draw up a table of current against length and record the current reading for each length ( repeat each reading at least twice  , preferably 3 times.)

Plot a graph of length against current.

Repeat this for different volt readings