Experiment to Verify Ohm’s Law Rolla Tyas Amalia Grade 11 “For a conductor at constant temperature, the current in the conductor is proportional to the potential difference across it.”IntroductionOhm’s law is used in electrical engineering to calculate the relationships betweencurrent, voltage and resistance. The calculations are required to design a safecircuit. Ohm’s law is apply in our every-day life in electrical things that we use,such as light bulbs, electric stoves, and others. Ohm’s law was discovered by ascientist named Georg Simon Ohm. It published in his paper titled The GalvanicCircuit Investigated Mathematically in 1827. Ohm’s principal discovery was thatthe amount of electric current through a metal conductor in a circuit is directlyproportional to the voltage across it, for any given temperature. Ohm expressedhis discovery in the form of a simple equation, describing how voltage, current,and resistance related to each other: V=IRHypothesisThe experiment setup consists of a simple circuit with a variable resistance andsimple power source, which are 3 batteries (1.5 Volt each). The diagram besideshows the single circuit that we will use for thisexperiment:We could choose a Voltage range and then varythe value of the resistance over the range. Asexpected from Ohm’s law, it will be seen thevoltage range and value of the resistancechosen will be linear and the value ofresistance will be perpendicular to the current.
ExperimentApparatus: 1. 4 varied value of resistors 2. Power supply 3. Connecting wires 4. MultimeterVariables: Independent: Resistance Dependent: Current Controlled: Electromotive forceProcedures: 1. Set up the apparatus to be the circuit as shown in diagram of hypothesis. 2. Set the value of electromotive force into 3 V. 3. Put the 12-ohm resistor and see the value of current in the Multimeter. 4. Change the 12-ohm resistor with 82 and 470-ohm resistor variedly and repeat step 3. 5. Change the value of electromotive force into 6 V. 6. Repeat steps 3 and 4 (use 56-ohm resistor instead of 12-ohm resistor, because the value of 12-ohm resistor is too small for 6V of electromotive force). 7. Record the data in this table: Experiment In Calculation Current Resistance Voltage V = IR 0.215 A 12 Ohm 3V 2.58 V 0.037 A 82 Ohm 3V 3.03 V 0.007 A 470 Ohm 3V 3.29 V 0.105 A 56 Ohm 6V 5.88 V 0.073 A 82 Ohm 6V 5.98 V 0.013 A 470 Ohm 6V 6.11 V
AnalysisFrom this experiment, we can see that the values of voltages depend on how bigare the values of resistors. The bigger the values of resistors, the bigger thevalues of electromotive force will be resulted. This shows that the voltage rangeand resistor value is linear to each other, while perpendicular with the value ofcurrent. For more clear details, see the table of the experiment data above.ConclusionThe value voltage range in a circuit will be linear with the value of resistorchosen, and perpendicular with the value of current resulted.