Essay, Pages 3 (611 words)
Once the electrons are moving this “flow” factor is called the Current and can be measured by the uppercase letter “I” or the symbol “A” (Amps). PotentialDifference Resistance= Current In my investigation we were finding out how resistance is affected by the legnth of a wire. For this we needed potential difference and current. When electrons move through a resistor they collide nwith stationery particles in the resistor. These collisions cause the resistor to heat up this can therefore change it’s resistence.
An LDR changes it’s resistance depending on how much light there is eg: In Bright light the resistance falls In darkness, the resistence is highest Thermistor( Tenperature-Dependent Resistor) A thermistor is similar to an LDR but it’s resistance depends on temperature eg: In hot conditions the resistance drops In cool conditions the resistance goes up There are some factors that affect the resistance: Legnth Of Wire: The longer the wire is, then larger it’s structure is meaning more positive ions, therefore creating more collisions between positive metal Ions and free vibrating electrons which creates more resistance.
Thickness of the wire
The thicker the wire is the more free electrons in the current can spread out moving over a larger area therefore there is a smaller chance of colliding with the positive Ions, thus it decreases the resistance. Voltage(potential difference) And Current in a circuit The higher the potential difference and the lower the current means higher resistance. Resistance (ohms) = Potential difference(V)/Current(Amps/A) Resistance (ohms) Legnth of wire(cm) The graph above shows how my graph should look in the end, I am predicting that as the legnth of wire increases so will the resistance.
The graph which I have done has a nice line of best fit with equal plots on both sides showing that my experiment was pretty reliable. I have also added in range bars to show my highest and my lowest resistance. The smaller the range bars are the more accurate my results are and the bigger my range bars are the less reliable my results are. At 20cm I seem to have an anomaly as my range bars are huge this means that I did something wrong with my experiment at 20cm. My method of approaching this investigation has been fairly good, as seeing my results I can confidently suggest that as the length of wire increases so will it’s resistance.
To improve my experiment, I could repeat the test more than 3 times e. g. : 5 or 10 times instead of 3, this will give me more reliable data as there will be a smaller chance of an anomaly occurring and will give me a better overall relationship between length and resistance. Another way I could improve my experiment is by keeping the temperature constant in possibly a thermostatic room, higher temperature= higher resistance this means that the temperature of the room I was in was less reliable as it could have gone up or down during my experiment.
Therefore a temperature controlled room would improve the reliability of my results. I am not able to say that my prediction is 100% correct as I have only used one type of wire (constantan), therefore I may only be able to say that as the length of constantan wire increases so does it’s resistance. I will need to do the same experiment with a different wire to prove this. I may also change the length of the wire (e. g. : increase by 5cm) to ensure that my prediction of whether the length for wire and resistance are in proportion and if my pattern is accurate and reliable, also to what extent they are reliable.