What effects the electrical resistance of a wire?

Authors Avatar

GCSE PHYSICS COURSEWORK                                                                  Moe Shimizu 11G

PLANNING :

The problem : What effects the electrical resistance of a wire ?

Background knoweledge : 

Resistance is measured by the following equation:

R = V / I

Ohm's law states that the amount of current flowing in a circuit is directly proportional to the voltage of the circuit and inversely proportional to the total resistance of the circuit.  For my experiment, Ohm’s Law shows that if the current increases or decreases, then the voltage will increase or decrease accordingly and propotionally.    Knowledge that I already have of Ohms law is how to measure resistance using a voltmeter and an ammeter. The law is usually expressed by the formula I = E/R, where I is the current in amperes, E is the electromotive force in volts (voltage), and R is the resistance in ohms. (This enables us to work out the resistance using the current and voltage:
R=V/I.)  I will measure resistance by using an ammeter for current and a voltmeter for voltage.

Energy from a cell is carried along through a circuit, because charged particles move within leads or connecting wires giving energy to another particle.  These charged particles are known as free electrons.  This is called electrical conduction. Connecting wires and leads are excellent conductors of electricity and do not affect the flow of these electrons. The tighter the electrons are packed, the easier it is for the electrical current to flow.   The electrons collide with atoms that are found in the bulb’s filament (the loss in kinetic energy allows the atoms of the filament to vibrate more powerfully and the filament becomes hotter.)  Therefore, there is an increase in resistance of the wire and a decrease in current.  A good conductor of electricity is copper.

Join now!

If resistance in a circuit increases, electric current decreases.  A variable resistor can be used to alter the current in a circuit.  In this experiment, I will vary the length of a wire (of a particular material) connected to a circuit.

Safety :

There are only a few safety precautions involved in this experiment.  The main problem is that a wire could possibly overheat (due to a high resistance) during the experiment.  Therefore, I should ensure that no-one and nothing is burnt.  To prevent over-heating of wires, I have decided to avoid leaving the circuit on for ...

This is a preview of the whole essay