OHMs prac report Essay Example for Free

OHMs prac report Essay Introduction: OHMS Law states that the current passing through a conductor between two points is directly proportional to the potential difference (i. e. voltage drop or voltage) across the two points, and inversely proportional to the resistance between them. The mathematical equation that describes this relationship is: Independent Variable: changing the resistance (OHMS) Dependant Variable: The current (A) is decreased because of the increasing resistors. Constant: The voltage is kept constant but is changed at the end of each test to make the investigation more accurate. Materials: Method: 1. Collect materials listed in above diagram 2. Set up apparatus shown above 3. Set the voltmeter to 1 volts and place the lead in the 5 OHMs resistor 4. Turn to the Power Pack and record the reading on the ammeter 5. Repeat step 3 and 4 2 more times. 6. Change the volts to 3,5,7,9,11,13 and 15, remembering to only record with the 5 OHMs resistor. 7. Record the results using the 5 OHM resistor 8. Repeat steps 4 7 but instead of using the 5 OHMs resistor, use 10 OHMs, 18 OHMs and 56OHMs resistors 9. Clean up all equipment and analyze the results Results: Current (A) Volts 5 OHMs 10 OHMs 18 OHMs 56 OHMs 1It can be seen from the Graph that as the volts increased and so did the resistors, the current was recorded lower that the previous. The highest current recorded was, 2. 557amps with a resistance of 5 OHMs and a voltage of 15 volts. The lowest current recorded was, 0. 017amps with a resistance of 56 OHMs and a voltage of 1. This shows that as the resistors increased the current was weaker, than of a low resistor at the same voltage. Using the Formula and rearranging the equation so R is the average value for the Resistor can be found. The Formula now would be . The Average resistor value for: The 5 OHMs resistor = 5. 857, The 10 OHMs resistor = 10. 340, the 18 OHMs Resistor = 18. 038 and the 56 OHMs resistor = 56. 238. Discussion: Systematic errors: The resistor not calibrated to the exact value displayed Ammeter not calibrated properly Voltage on battery pack not correctly calibrated properly Random errors: Leaving the resistors on to long causing the resistors to over heat and decrease the resistance. Loss of resistance to the resistors due to ware and tare on the resistors over a long period of time. Damaged equipment. Humidity and room temperature Improvements: There are some possible improvements that could be made to improve the results and practical experiment. The Equipment should be checked prior to the practical to reduce errors during the experiment. Also introducing more accurate results by recording the results ten times, instead of five, and work out the average. Use digital ammeters to measure the current. Compare the results to other practicals that were conducted and compare views and data. The Results: It can be seen from the Graph that as the volts increased and so did the resistors, the current was recorded lower that the previous. The highest current recorded was, 2. 557amps with a resistance of 5 OHMs and a voltage of 15 volts. The lowest current recorded was, 0. 017amps with a resistance of 56 OHMs and a voltage of 1. This shows that as the resistors increased the current was weaker, than of a low resistor at the same voltage. Conclusion: The Hypothesis is correct, as the volts and the resistance was increased, the current decreased. 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.