Parameters

Introduction

Voltage, Current and Resistance

All multimeters measure voltage, current and resistance. Some multimeters measure even more electrical parameters. For example, the Agilent 34401A also measures AC frequency; however, we will not utilize this capacity in todays lab.

Voltage is measured in volts (V). You always measure a voltage change: i.e., the voltage difference between two points in a circuit.

Current, measured in Amperes (A), is the net amount of electrical charge flowing past a point per second.

Resistance, measured in Ohms (Ω), limits the flow of current.

It is unlikely that you will have covered all of these parameters in class prior to laboratory. To gain an intuitive perspective, it is helpful to think of fluids flowing in a pipe. Resistance would correspond to a valve: a large electrical resistor would be analogous to a valve that is adjusted more towards the off position. The pipes would correspond to the electrical wires: think of wires as tubes through which current flows. Voltage would correspond to fluid pressure: just as no fluid flow is possible across a valve without a pressure drop, no current flow is possible across a resistor without a voltage drop.