Measurement of Resistance and Ohm’s Law

LAB 01
Measurement of Resistance and Ohm’s Law

Section : 04
Instructor’s Name : BERNA DÜNDAR
Experiment Date : 26/02/2014
Submission Date : 05/03/2014

Measurement of Resistance and Ohm’s Law
Department of Physics,Işık University
Meşrutiyet Köyü,Üniversite Sokağı,No:2 34980 Şile,İstanbul

Abstract

In this experiment we used two multimeters, a set of resistors, a bundle of connecting wires and a DC power supply. By this experiment we learned how to use the electrical instruments, simple circuit elements and we studied Ohm’s law.

Theory

In electrical circuits, we are concerned with the flow of electrical current around closed loops made up of wires, meters and other components. For this unit we measured and calculated electrical quantities such as direct current, voltage and resistance.
Current
Electrical current is the rate at which electrical charge flows around a circuit. It is measured in units of amperes (A) by ammeters.
Potential Difference (voltage)
Electrical charge tends to move from points of high potential to points of low potential. The difference in potential between two points is called the potential difference or voltage and is measured in units of volts (V).
Resistance
For many devices, it is found that the potential difference appearing across a device is proportional to the current flowing through it. The connecting relationships is known as Ohm’s law and is written:V = IR where R is the resistance and is measured in ohms (Ω).

Procedure

First, we pick one of the resistors and read its resistance by using color codes. After we read other resistors resistance we recorded the results. Then to measure the resistance of the resistor we used a multimeter and recorded the results. After that we compare the color band reading with the measured value of the resistance and we found the percentage error.

Afterwards we set up the electrical circuit. We recorded the current through and the voltage across the resistor. To calculate the resistance we used Ohm’s law. We found the percentage error by comparing the color band reading with the measured value of the resistance again. We did the same steps for other resistors. After that we randomly picked a resistor to use in the same circuit, and set the output of the power supply to 12.0V. We recorded the result and did the same steps for 10.0V, 8.0V, 6.0V and 4.0V. To find the resistance of the circuit we used Ohm’s law again.

Conclusion

We were able to prove Ohm’s law for resistances V = IR. We checked our results against the proper values from the colour codes and they agreed to with in experimental error. In future experiments it would be best to use better equipment, that is more up date meters.

Tables and Graphs