Ohm’s law and I-V characteristics with current and voltage sensors

Ohm’s law is a fundamental law of electricity which describes how electrical circuits behave. It is introduced with electric circuits in introductory physics courses. In the laboratory it is verified and unknown constant resistances are determined by measuring the voltage across and the current through them. In the past, it is customary to use a voltmeter and an ammeter to measure the voltage and current with limited accuracy and eaze. Current-Voltage (I-V) characteristics of diodes are introduced as an extension but seldom in the laboratory due to its complexities in measuring small currents and voltages, simultaneously. Observing and studying the I-V characteristics is much easier and straightforward with currently available interfaces and current & voltage sensors in an introductory physics laboratory. We use PASCO’s 850 interface with its current and voltage sensors to observe the I-V characteristics of various circuit elements with ease and elegant results are obtained. The “Keep Mode” feature of the Capstone software is used to control the data. Data and curves are displayed instantly as the current and voltage are changed using a variable power supply. Current-Voltage characteristics of a resistor, an incandescent light bulb, and a silicon diode will be presented.