Investigating the current through a wire Essay Example Essay Example

Investigating the current through a wire Essay Example Paper Investigating the current through a wire Essay Introduction I am investigating how the length of a wire affects the current and resistance of a wire. Apparatus: 1. power supply of 2 V 2. Ammeter Investigating the current through a wire Essay Body Paragraphs 3. Voltmeter 4. Circuit Wires 5. Nichrome Wire 6. A meter ruler 7. Sellotape 8. Digital Voltmeter 9. Crocodile Clips Diagram: Detailed Method: I will set up the circuit as shown in the diagram above. Then I will start the experiment by attaching the 100 cm of nichrome wire to the metre ruler carefully, so there are no twists in the wire, which would affect the exactness of my results. Then I will switch on the power supply and make sure that a constant voltage is flowing through the circuit. I will then record the current flowing through the wire from a digital .. using different lengths. I will record the current every 10 cm. From a 100 cm down to a 90cm From 90cm down to 80cm, from 80cm down to 70cm, from 70cm down to 60cm, from 60cm down to 50cm, from 50cm down to 40cm, from 40cm down to 30cm, from 30cm down to 20cm, from 20cm down to 10cm. Since the wire will heat up I will wait a while after each measurement, so my results will not be influenced by the heat of the wire, whish sh ould make the experiment a fair test. I will repeat this experiment 5 times, so I can take the average current for each length. Prediction: I predict that if the length of a wire increases, the resistance will also increase in proportion to the length. The larger the wire, the more atoms present, so it is more likely that electrons will collide with the atoms. Resistance occurs when the electrons traveling along the wire collide with the atoms of the wire. These collisions slow down the flow of electrons causing resistance. Resistance is a measure of how hard it is to move the electrons through the wire. If the length of a wire is doubled, the electrons bump into twice as many atoms, so the resistance will be doubled. In my experiment factors affecting the result will be 1. Temperature : If the wire is heated up the atoms in the wire will start to vibrate because the energy is increased. This causes more collisions between the electrons and the atoms because the atoms are moving int o the path of the electrons. This increase in collisions means that the resistance will increase. 2. Wire length : If the length of the wire is increased then the resistance will also increase because the electrons will have a longer distance to travel and so more collisions will occur. Due to this the length increase should be proportional to the resistance increase. The Ohm’s law Ohm’s Law is a formulation of the relationship of voltage, current, and resistance, expressed as: V = I x R Where: V is the Voltage measured in volts I is the Current measured in amperes R is the resistance measured in Ohms Therefore: Volts = Amps times Resistance Results: I will put my results in a table to show my different measurements. I made the experiment 5 times with each wire. I used a thicker and a thinner nichrome wire to show the difference. I will put my results of each attempt in a table, showing the length, voltage and current. Then I will calculate the resistance using the equ ation R = V / I. Results of the thicker wire Length in cm Voltage in V Current in A Resistance in Ohms 10 2 0.90, 0.98, 0.94, 0.94, 0.94 2.22, 2.04, 2.12, 2.12, 2.12 20 2 0.55, 0.69, 0.60, 0.68, 0.64 3.63, 2.89, 3.33, 2.94, 3.12 30 2 0.4, 0.47, 0.48, 0.48, 0.47 5.00, 4.25, 4.16, 4.16, 4.25 40 2 0.31, 0.39, 0.38, 0.38, 0.35 6.45, 5.12, 5.26, 5.26, 5.71 50 2 0.26, 0.32, 0.31, 0.29, 0.30 7.69, 6.25, 6.45, 6.89, 6.67 60 2 0.24, 0.26, 0.27, 0.26, 0.27 8.33, 7.69, 7.40, 7.69, 7.40 70 2 0.23, 0.22, 0.24, 0.24, 0.23 8.69, 9.09, 8.33, 8.33, 8.69 80 2 0.21, 0.20, 0.21, 0.21, 0.21 9.52, 10.00, 9.52, 9.52, 9.52 90 2 0.19, 0.18, 0.19, 0.18, 0.19 10.52, 11.11, 10.52, 11.11, 10.52 100 2 0.16, 0.16, 0.17, 0.17, 0.16 12.50, 12.50, 1176, 11.76, 12.50 Now I will put the results of the thinner wire in a table Results of the thinner wire Length in cm Voltage in V Current in A Resistance in Ohms 10 1 0.30, 0.30, 0.31, 0.29, 0.31 3.33, 3.33, 3.22, 3.44, 3.22 20 1 0.19, 0.19, 0.20, 0.20, 0.20, 5.26, 5.26, 5.00, 5.00, 5.00 30 1 0.15, 0.14, 0.15, 0.15, 0.15 6.66, 7.14, 6.67, 6.67, 6.67 40 1 0.12, 0.11, 0.12, 0.11, 0.12 8.33, 90.9, 8.33, 9.09, 8.33 50 1 0.10, 0.10, 0.10, 0.10, 0.10 10.00, 10.00, 10.00, 10.00, 10.00 60 1 0.07, 0.09, 0.09, 0.09, 0.08 14.28, 11.11, 11.11, 11.11, 12.50 70 1 0.07, 0.09, 0.07, 0.08, 0.07 14.2811.11, 14.28, 12.50, 14.28 80 1 0.07, 0.07, 0.06, 0.07, 0.07 14.2814.28, 16.67, 14.28, 14.28 90 1 0.06, 0.05, 0.06, 0.06, 0.06 16.67, 20.00, 16.67, 16.67, 16.67 100 1 0.05, 0.05, 0.05, 0.05, 0.05 20.00, 20.00, 20.00, 20.00, 20.00 I will now calculate the average current and resistance for each length and then draw a graph with these results. Average results of the thicker wire: Length in cm Voltage in Volts Current in Amps Resistance in Ohms 10 2 0.94 2.124 20 2 0.632 3.182 30 2 0.46 4.364 40 2 0.362 5.56 50 2 0.296 6.79 60 2 0.26 7.702 70 2 0.232 8.614 80 2 0.208 9.616 90 2 0.186 10.756 100 2 0.164 12.204 Average results of the thinner wire: Length in cm Voltage in Volt s Current in Amps Resistance in Ohms 10 1 0.302 3.296 20 1 0.190 5.104 30 1 0.148 6.762 40 1 0.116 8.634 50 1 0.098 10.00 60 1 0.082 12.022 70 1 0.072 13.29 80 1 0.068 14.758 90 1 0.058 17.336 100 1 0.050 20.00 Analysing As you can see, on the graph â€Å"length against average resistance of the thicker nichrome wire† the length is proportional to the resistance of the thicker nichrome wire. The graph is almost a straight line, which means that the resistance is proportional to the length. I predicted that if the length of a wire increases, the resistance will also increase in proportion to the length. The larger the wire, the more atoms present, so it is more likely that electrons will collide with the atoms. Also if the length of the wire was trebled or quadrupled then the resistance would also treble or quadruple. The graph â€Å"Length against Average resistance of the thinner nichrome wire† is shown. Again, the graph is almost a straight line, which means that the resistance is proportional to the length. This proves again that my prediction was correct. Also if the length of the wire was trebled or quadrupled then the resistance would also treble or quadruple. Evaluation I can see from my graph that my results were quite reliable. All the points, lie almost on a straight line apart from one being very close to that line. The reason for this could have been due to a number of different factors. Firstly the temperature of the wire changed during my experiment, as the wire got hotter, which could have led to slight errors in my result. There also were small twists in the wire, which affected the accuracy of my result as well. However I repeated the experiment 5 times and then calculated the average current through the wire. The crocodile clips could have affected the fairness of the experiment as well. They are a different type of metal from the nichrome wire and may have different properties which means a different resistance. Most errors in my experiment probably occurred while measuring the wire. This is because it was not very easy to hold a piece of wire straight, while holding it next to a ruler and then trying to connect the crocodile clips to the wire. Also I do not think that the crocodile clips were always connected correctly to the wire with a good connection. This also meant that they were easy to move around on the wire changing the length of it It was hard for me to read the Current since it changed between two numbers on the ammeter. It took a long time until I could decide on the final current, which affected the accuracy of my result again, since the wire got hotter. I don’t think that taking any more results could have made them more accurate. I could have improved my results by writing down the change in voltage and see how it affects my results, or taking the measurements every 5 cm. Further experiments I could have done related to the resistance of a wire could be to see whether the material w ould make a difference in the resistance of a wire. I don’t think I could really improve on the way the experiment was done. I also found that the experiment was quite easy to set up, as it was simple and uncomplicated. 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