Physics investigation We know that when we send electricity from the power stations to our homes some of the electrical energy is “lost” due to the resistance of the wire. To reduce this loss we send the energy at a high voltage and a low current. In this investigation we want you to find out how we can reduce the resistance of the wire. Preliminary investigation In order for us to do our final investigation we must do a preliminary investigation. This way I can find out how the temperature affects the resistance of the wire. And so I know what current measurements to use in our final experiment.
Variables: – cross section Length Material Temperature Voltage (volts) Current (amps) Resistance Conclusion for graph The results from the graph show us that the resistance stays the same. However the maximum current that we could use for the experiment is 1-amp. At around this level the current heats the wire causing the sellotape to melt and the wood could burn.
The wire expands and starts to loose shape. Going higher than this would be too dangerous and it would make it impossible to be sure the results are valid. Prediction In a metal there are electrons and atoms. Electricity is conducted through the wire by means of free electrons gaining energy and flowing freely through the conductors. As they flow freely through these conductors there is a certain chance of them being captured by the metal atoms. As we know free electrons are responsible for conduction, the more there are the better the conductor so the lower the resistance.
However if lots of electrons are captured by the atoms then there wont be as many for conduction so the resistance will be greater. Resistance results in energy loss as heat. I predict that if we increase the length of the wire then the larger the resistance will be because there will be more chance of the particles being captured. However if the wire was shortened then there would be less chance of the electrons being captured so not as much energy would be lost as heat. The temperature of the wire should effect the resistance because as the temperature increases the atoms in the metal gain more energy, causing them to vibrate a lot more.