Electricity has three features that include current, voltage and resistance. Current is the flow of electrons round a circuit that is measured by the ammeter in amps (A). Whilst the voltage, refer to as potential difference, is the driving force that circulates the current around the circuit that acts like an electrical pressure. The unit of measurement for this is Volts (V), which is measured by a voltmeter.

Resistance is a force that slows down the current; consequently it slows down the flow of current. This is measured in Ohms (W). Between the voltage and resistance there is equilibrium, where the voltage impels the current, whereas the resistance is opposing this electrical pressure. The relative sizes of the voltage and resistance decide how big the current will be. Increasing the voltage allows more current to flow, whilst increasing the resistance would decrease the amount of current flowing round the circuit. Discovered by George Ohm in 1826, the current is in direct relative amounts to the potential difference.

If the temperature is kept constant as well as other conditions, Ohms law is obeyed. The graph on the side illustrates the current through a resistor is proportional to the voltage. V = IR gives the formula for Ohms law. In order for current to flow it requires electrons to carry the electric current. The electrons are the negative charge that can freely move about. Within metals there are a sea of electrons that can carry the electric current, which is reason why they conduct so well and are used for many purposes, such as wires.

Factors During the investigation there will be many factors that will affect the resistance in a wire. These factors include: . Length of wire - If the wire length increases, the distance for the electrons to pass through would take a longer period of time since the electrons collide more with atoms of the wire. As a result there is an increase in resistance as the number of collisions cause the electrons to flow slowly, which justifies the term for resistance. Conversely if the length of the wire is shortened, the time taken for electrons to travel is reduced given that there are not as many electrons colliding with atoms. As results there are a small number of collisions, hence reduces the resistance...

Thickness of wire - A wider breadth of the wire causes atoms within the wire to expand a small distance between each other. Subsequently the gap between the atoms permits a more frequent flow of electrons to pass through. As a result the resistance is reduced. However if the width decreases, the outcomes would become an increase in resistance since atoms are closer, which closes the gap for electrons to pass more frequently without any collisions... Temperature of wire - An increase in temperature would provide a supply of heat. This gives the atoms within the wire to acquire kinetic energy.

Thus the atoms vibrate more, which is passed on to another atom etc. The vibrations cause more collisions since electrons collide with the vibrating atoms. The outcome would be an increase in resistance... Material of wire - Different materials may affect the resistance of the wire.

This factor relies on the material on whether the wire is Nichrome or Constantan. Nichrome is made up nickel and chrome, which are used for the purpose of heating elements. Yet the resistance varies under temperatures between 1-100 oC. Whilst Constantan is made up of nickel and copper that are used for making resistant elements however it is known to melt under high temperatures.