The factors affecting the current flow through a conductor at a constant temperature.

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I need to investigate the factors affecting the current flow through a conductor at a constant temperature.


Resistance is a force found in currents that opposes the flow of electrons around a circuit. When this occurs energy is needed to push the charged particles around the circuit. The circuit itself can resist the flow of particles if the wires are either very thin or very long. E.g. the filament across an electric bulb is quite thin as needs to resist the flow of particles for the bulb to glow. Resistance is measured in Ohm’s because George Ohm discovered it.


As I need to investigate the factors affecting current in a circuit I need to vary something connected to current. The ideal choice is Ohm’s law (resistance = voltage/Current) because voltage and resistance are easily changed to vary the current. Ohm’s law is sometimes written like this:

V = Voltage

C = Current

R = Resistance

Current is the flow of electrons in a circuit. This is what an ammeter measures. There are 2 types of ammeter, digital and analogue. Digital readers are easier to read because the current is displayed as a number.

Voltage is the amount of energy transferred by each coulomb of charge as it passes round the circuit.

Resistance affects the flow of electrons in a circuit. If you increase the resistance in a circuit it is more difficult for the electrons to flow. It is almost like an athlete running a track, he runs at a constant speed until he reaches some hurdles, this slows him down because they are obstacles to avoid, it is exactly the same in a circuit for the electrons.

The components in a circuit can also increase resistance. The electrons have to flow through more hurdles/ resistance, slowing it down and decreasing the reading on the ammeter.


I will have to take several safety pre-cautions. I will have to check that there is not impure water around the circuit because it presents a danger of a nasty shock. All long hair will have to be tied up to stop it interfering with the equipment. All obstacles like chairs will have to be placed under the desk to prevent accidents.

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The risk of overheating in the circuit was minimilised by using a long enough length of wire and by using less than 3 volts.

Fair Test

There are many variables affecting this circuit. According to Ohm’s law we need to keep the circuit at a constant temperature to ensure accurate results. This will be accomplished by turning off the circuit when it is not in use. We will also need to keep all of the equipment the same. This will be easy to do if all of the results are taken on the same day. The same readers ...

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