The length and width Essay Example for Free

The length and width Essay This is due to the electron s for a long distance than before. Thus we say the resistance increases. When the width of the wire increases, the hindrance for the flow of electrons increases. Because the space through which electrons flow increases. Thus we say that the resistance decreases Preliminary Width of the wire ( mm) Length of wire (mm) Voltage (V) Current (A) Resistance ( ? ). From this preliminary experiment I will increase the length of the wire up to 30cm in order to get the reliable results. The reason why I chose the thin wire is because to get a high resistance and therefore it is easy to measure. I have used three different widths because I want to find out width gives the best results. To get precise measurement I will measure the value of the current and voltage up to two decimal places. Obtaining evidence This is how the set up of my apparatus looks like. First I join everything together and check if everything is in the right place. Then I adjust the 30cm length of wire to the length of 5cm, 10cm, 15cm, 20cm and 25cm, with the help of the crocodile clip. After that I change the resistance by means of the variable resister to get an accurate measurement /result of the current and voltage for each length. Actual experiment Width of the wire ( mm) Length of wire (mm) Voltage (V) Current (A) Resistance ( ? ) Safety When the experiment has been started the wire becomes hot. The safety here is to put the things (e. g. paper, books, exercise books etc. which are inflammable) to a side, so that it cannot come into contact with the wire. After finishing the experiment turn the current off. Length (cm) Average Resistance   I can use the results not with 100% certainty; I can rely only on 60%. This is in regard to change in resistance caused by the charge on the length of the wire. This is in regard to the change in resistance caused by the change in length of the wire. As far as concerning the change in resistance due to change the width of the wire are anomalous. Analysis My experiment shows longer the wire higher the resistance. That is, when the length of the wire increases, resistance increases. Resistance is directly proportional to the length of the wire. Resistance of wire ? length of the wire Resistance = k x length Observation K Constant First 0. 21/5 0. 04 Second 0. 45/10 0. 04 Third 0. 58/15 0. 04 Fourth 0. 87/20 0. 04 Fifth 0. 95/25 0. 04 From the above table, this numerical calculations shows that the resistance is directly proportional to the length of the wire. If I double the length of the wire, the resistance also get doubled as a result. My experiment ,in respect of the conductor with the length of 15cm, shows that the current flow is directly proportional to the potential difference. The voltage ? current In respect of other length of the conductors (5cm, 10cm, 15cm, 20cm and 25cm) there is a variation in the second decimal of the constant figure. These discrepancies may be due to the slight changes of the external temperature of the conductor when current passes through the conductors. It may be also due to the reading of the ammeter and voltmeter by the eye. Evaluation My results are reasonably good as far as concerning the change of resistance due to the change in length of the conductor. My results are fairly good as far as concerning the Ohms law. That is, the current passes through the conductor is directly proportional to the potential difference across the conductor provided the temperature remains constant. My results were not at all good as far as concerning changes of the resistance due to changes in the width of the conductor. My graph which shows the resistance and length of the conductor is a straight line which passes through the origin and 3 points. Two points stays out of the line. For the variation of the resistant, I could not draw one line on one graph and I have drawn 5 lines on one graph. I could not draw my conclusion on the graph because the variations of the width are not great enough to produce significant variation in the resistance. Only 2 points fell on the line and the third one slipped out. If the straight line passes through 3 points on the graph we can depend on the reliability (length against resistance graph). In contrast in the width against resistance graph, only 2 points falls on the straight line. Therefore I cannot depend on the reliability. This anomaly is due to the fact that the wires which I have chosen are not considerably vary in thickness (width). Another way of doing that is to take reading using the constantan wire and then the second reading connecting 2 wires as shown in the prediction and keep on doing this for 3, 4 wires. The anomalous points on the graph (2 points) may be due to the crocodile clips which were not properly attached. There may be lack of specification in observing the ammeter and voltmeter with the eye. There may be fluctuation in the external and in the internal temperature of the conductor. I can use a conductor made of nichrome which is an alloy of 60% nickel, 24% iron and 16% chromium. Accurate laboratory standard are made from a coil of resistance wire inside a protective plastic case. 1 Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.