Resistance Coursework

Topics: Ohm's law, Electric current, Electrical resistance Pages: 4 (1205 words) Published: April 20, 2005
Resistance coursework

Aim: My aim is to find out which factors affect the resistance of wire and how they affect them.

Ohm's Law:
Ohm's law is also relevant to know of Ohm's Law, which states that the current through a metallic conductor (e.g. wire) at a constant temperature is proportional to the potential difference (voltage). Therefore V ¸ I is constant. This means that the resistance of a metallic conductor is constant providing that the temperature also remains constant. Furthermore, the resistance of a metal increases as its temperature increases. This is because at higher temperatures, the particles of the conductor are moving around more quickly, thus increasing the likelihood of collisions with the free electrons. Resistance is the ratio of Voltage : Current and we calculate it by using the equation R=V/I.

Material of wire: In my experiment I will be using wire, because it has a high resistance. This could be either it has a closer ions or more ions than other metals. For example Copper has a low resistance due to the arrangement of its ions.

Temperature: A rise in temperature causes ions inside the metal to vibrate more causing electrons to collide into them this builds resistance; therefore the electrons find it harder to get through the wire. The greater the temperature the greater the resistance because electrons are colliding more causing friction. Therefore the relationship between them is directly proportional.

Cross section of the wire: The thicker the wire the easier it is for the electrons to go past. The thinner the wire, the smaller the area the electrons have to pass through. This means that they collide more often and as a result sacrifice more of their energy to the neighbouring particles in the wire. The cross section of the wire and the resistance is inversely proportional this means that the greater the thickness of the wire the lower the resistance.

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