Ohms law is named after george simon ohm a german physicist. The german physicist georg simon ohm 17871854 was the first to demonstrate experimentally that the current in a metal wire is directly proportional to the voltage applied. If a voltmeter is used to measure the voltage v across an unknown resistance r, and an ammeter is used to measure the current i through the same unknown resistance, then r would be given by r vi. Enter the data from table 2 into excel, and plot it with current on the xaxis and voltage on the yaxis. Using the currents obtained in step 1 of the analysis.
Be sure to leave the legend displayed on your graph. In this lab, you will use a variable power supply to subject a resistor of known resistance to a variety of voltages. For this experiment, we will be studying a material known to obey ohm s law. Lets start off by understanding the types of errors. Experiment 3 ohms law, measurement of voltage, current and. Ohm s law states that the resistance r is related to the voltage v and the current i across the resistor according to the following equation. Click the box next to the current data for r2 and click. The objective of this lab is to apply ohm s law to both series and parallel dc circuits. Calculations verification of ohms law report the theoretical calculations are achieved from the original formula, v ir.
Ohms law lab report with graph, observations and verification. This chapter is largely a tutorial on handling experimental errors of measurement. Ohms law is the fundamental law of electrical engineering. The real practically calculated red color vs the theoretical values blue are plotted on the graph. An ohm s law experiment for this experiment, we want to use a 9 volt battery to power an led. Two resistors will be used with resistances varying by nearly three orders of magnitude. The website is a dedicated resource for ohms law, calculation tools, applications and theoretical calculations on ohms law. The overall experiment went well, and it succeeded the purpose of the trial which was how changing the voltage could affect the amount of current flowing in a series circuit while being able to prove ohms law. Imagine that we are trying to determine an unknown resistance using this law and are. I had a quick look but i dont understand experiment 3.
There are many ways to write up a lab report, none of them superior to. Experiment 3 ohms law, measurement of voltage, current. Measurement and error analysis homework reading prior to lab. Ohms law is an empirical formula which relates the voltage drop across a resistor to the current through. The circuit appears to show two resistors in series but where they calculate r value from mathematical formula it assumes they are in parallel. This is a very simple experiment enabling to focus on the philosophy of experimentation, error analysis. To collect the data, experiment needs to be performed using three different types of materials,material 1, material 2 and material 3. Print 1 copy of the report page to start your lab report. In addition, a dc voltmeter and a dc ammeter must be used properly in order to correctly measure the current and voltage present in the two circuits that are to be built. While ohms law for a part of a circuit offers no help in experiment, it also has.
Imagine that we are trying to determine an unknown resistance using this law and are using the philips meter to measure the voltage. As you may have noticed, ohm s law is an equation in the form of a straight line. For this experiment current controls need to be turned completely counterclockwise we will later adjust the current to 1a. Nov 14, 2010 the aim of experiment is to investigate the relationship between voltage and current for both a light bulb filament and an exposed filament. For each trial, calculate the percent of difference between the calculated and measured current in the circuit. By knowing this simple law, you understand the concept that is the basis for the analysis of any electrical circuit. Ohms law and kirchoffs laws were found to be valid after comparing the results from all three tests. Ohm discovered a linear relationship between voltage and current in many circuit elements. V i r where v is voltage volts,i is current amps, andr is the resistance of the circuit element that we now measure in the unit of ohms. The aim of experiment is to investigate the relationship between voltage and current for both a light bulb filament and an exposed filament. Resistance, ohms law, and i v curves lab report studocu. The watt w is a measurement of power in an electrical circuit. As always, you can find a summary online at hyperphysics1. The objective of this lab is to apply ohms law to both series and parallel dc circuits.
The measurements were made by highschool students in a. Analysis for most single solid materials at constant temperature, the relation between current and voltage is linear, making it useful to define resistance and ohms law. Set up currant and voltage ranges in the graph by using ohms law. Always use pretested precision resistors with extremely low tolerance, gold band or stated tolerance andor precision potentiometers for variable resistances, unless it is used for determining the unknown variable resistance.
Ohms law for electrical resistance, v ir, states the relationship between current, voltage, and electrical resistance. Comparison of the results with experiment and with a simplified analysis using torricellis law is made. Go to graph mode by dragging and dropping the graph from the left panel. Pdf difficulties in learning ohms law suggest a need to refocus it from the law for a part of the circuit to the law for the whole. Make sure the labpro interface is plugged into the usb port of the computer, its power supply is plugged in, and the interface is turned on. Since, temperature is a factor affecting resistance, a. Objectiveto experimentally verify ohms law through measurement and to confirm findings by comparingmeasured values with prediction. One such advance was made by a german physicist named georg simon ohm. For the final part of the experiment, close out of the ohms law file, and open the second ohms law file. Then, solve the system to obtain a theoretical value for each current. The procedure involves using a light bulb, which when an electric current passes through it begins to heat up. When the green power button is pushed in, the power supply is on. Aim of experiment the main purpose of this laboratory experiment is.
P power is the amount of current times the voltage. Experiment investigate the validity of ohms law aim. Wires have resistance that depend on wire size, length, and type of material. He finally published the law in 1827 and generalized his observations in single statement.
In addition, a dc voltmeter and a dc ammeter must be used properly in order to correctly measure the current and voltage present in the two circuits that are. Sep 15, 2012 for the first experiment, lets consider the measurement at the bottom of the table. To verify ohms law, which defines the relationship between voltage, current and resistance in a series circuit. Experimental verification of kirchhoffs voltage law and.
Voltage controls completely clockwise notice that there is a. Hookes law experiment hookes law experiment and analysis. Kirchoffs laws deal with the voltage and current in the circuit. Verification of ohms law, kirchoffs voltage law and. Voltage controls completely clockwise notice that there is a coarse and fine adjustment for both current and voltage. Construct a circuit using resistors, wires and a breadboard from a circuit diagram. The experiment on the hookes law will help to determine the behaviour of three different elastic materials, and help to investigate the differences of their behaviour around their elastic regions. Appendix b, appendix c dmm objective the objective of this lab is to determine the resistance of several resistors by applying ohms law. Your objective will be to test ohms law, which asserts that the resulting current through the resistor as well as the rest of the circuit is proportional to the applied voltage. Students will also be introduced to the resistor color code and refresh their graphing skills. Students will be expected to give details of equipment used, assembly of equipment, data collection, data manipulation including graphs where relevant. The summary report includes a short discussion of the results after processing the data gathered.
Experimental errors and error analysis wolfram language. Exploring ohms law in parallel and series circuits weconsider thatall resistance loads were similar in thecircuits, can obtain total current in the parallel circuit is 9 times higher than the electric current in the series. Electronic devices and to see whether they satisfy ohms law. Experimental verification of kirchhoffs voltage law and kirchhoffs current law abstract we have experimentally tested kirchhoffs voltage law and kirchhoffs current law by measuring the sum of the voltage drops around several closed paths, and the sum of the currents at several nodes, in two resistive circuits. Seminar assignments ohms law abstract and discussion studocu.
The current flowing through the resistor is directly proportional to the voltage applied across it. The purpose of this measurement is to verify ohms law vir for constant voltages and constant currents. The attached lab report is an example of what is considered an appropriate lab report in this course. Experiment 2 ohm s law print 1 copy of the report page to start your lab report print 2 copies of the data page file object. For each trial, calculate the expected current based on the resistance and measured voltage using ohms law. Nov 14, 2014 the experiment on the hookes law will help to determine the behaviour of three different elastic materials, and help to investigate the differences of their behaviour around their elastic regions. Much of the material has been extensively tested with science undergraduates at a variety of levels at the university of toronto.
The current that flows through most substances is directly proportional to the voltage v applied to it. Here r is the reciprocal slope of your graph, and has units of ohms volts amperes. Leds are fragile and can only have a certain amount of current flowing through them before they burn out. Theoryohms law states that in a resistive circuit, when the resistance is kept constant, the current through theresistor is directly. If youre looking to study further into more complex applications of ohm s law and the design of electrical circuits, be sure to check out the following hands on activities. The current measurement in the fluke manual has an error of 1 %. Physics 263 sample lab report the attached lab report is an. This lab activity will challenge you to verify ohm s law in a variety of. Ohms law states that the total current in a circuit i is equal to the total impressed voltage e divided by the total series resistance r. To study ohm s law for dc circuits, to learn basic construction and measurement of electric.
Lab 3 dc circuits and ohms law introduction during the nineteenth century so many advances were made in understanding the electrical nature of matter that it has been called the age of electricity. Electronic devices and to see whether they satisfy ohm s law. Seminar assignments ohms law abstract and discussion. This article presents the complete ohms law lab report. Whole books can and have been written on this topic but here we distill the topic down to the essentials. The letter p represents power in ohms law formula while watts is the unit of measurement. In the next experiment well try a familiar experiment to measure g and do the calculations using the rules weve just discussed.
Ohms law by the end of this experiment, the student must come up with a summary report for the experiment. What errors may happen during the experiment of ohms law. If the connections are soldered, then coldsolder joints can be a contributing factor to errors or poor connections in general. Ohms law states that the resistance r is related to the voltage v and the current i across the resistor according to the following equation.
Experiment 2 ohms law print 1 copy of the report page to start your lab report print 2 copies of the data page file object. Students will also be expected to know the conclusion or result of an experiment and appropriate precautions. Theoryohms law states that in a resistive circuit, when the resistance is kept constant, the current through theresistor is directly proportional to the voltage across the resistor. Wires add series resistance to circuits, just as good and bad connections add also. You can also verify them from the basic ohms law calculator. Students will become familiar with dc potentiometers circuits and ohms law. Verification of ohms law qassim university college of engineering phys.
Calculate the current from a constant 5 volt input by using equation 1. Youll also learn to obtain quite accurate readings. Record your results in your data table, and be sure to show a sample calculation. Recapitulating basic measurement and error analysis skills. The student must be able to do a regression analysis that is appropriate to the experiment. Experiment investigate the validity of ohm s law aim. Power supply for this experiment current controls need to be turned completely counterclockwise we will later adjust the current to 1a. The purpose of this measurement is to verify ohms law vir for. An ohms law experiment for this experiment, we want to use a 9 volt battery to power an led. The units youll use today are kilohms milliamperes k. Since, temperature is a factor affecting resistance, a drawback of the procedure is. Use the scopes builtin analysis tools to determine the voltage and current for the ten. One of the fundamental rules for electrical engineers is ohms law, named for georg simon ohm 17891854.
The current flowing through a constant resistor is directly proportional to the voltage applied to its ends. It relates the current flowing through any resistor to the voltage applied to its ends. Choose voltage in vertical axis and current in horizontal axis. This lab activity will challenge you to verify ohms law in a variety of. A weakness in my experiment is my graph of the results. To study ohms law for dc circuits, to learn basic construction and measurement of electric. If youre looking to study further into more complex applications of ohms law and the design of electrical circuits, be sure to check out the following hands on activities. Ohms law iiiresistors in series and parallel however, all wires that make connections and the connections themselves qualify as series resistance. Ohm performed repeated experiments on a resistor, applied different voltages, measured current and found relationship between these quantities. For the first circuit, use equations 1 and 2 to write a system of linear equations that may be solved for the current in each branch of the circuit.
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