Chapter 6: Electrical Measurements—Meters

Vocabulary-style flashcards covering electrical measurement tools, circuit testing terms, and meter operation as described in Chapter 6.

Analog meter

A type of meter that uses a graduated scale with a pointer to detect and measure the action of electrons.

Digital meter

A meter that provides a reading in numerical form, typically offering higher accuracy and easier readability than analog versions.

Terminal polarity

The identification of meter connections where a red terminal represents positive and a black terminal represents negative.

Zero adjustment screw

A small screw located on the front of an analog meter used to align the pointer to zero before measurement.

Ammeter

A flow meter used to measure the number of electrons flowing past a given point in a circuit, connected in series.

Voltmeter

A meter used to measure the difference of potential or electrical pressure between two points, connected in parallel.

Ohmmeter

A meter used to measure resistance by applying a voltage across a component and monitoring the induced current flow.

Multimeter

A single instrument that combines the functions of a voltmeter, ammeter, and ohmmeter.

Volt-ohm-milliammeter (VOM)

The name given to an analog version of a multimeter.

Digital multimeter (DMM)

A multimeter that uses a digital readout instead of a meter movement, often featuring a four-digit display.

Zero ohm control

A control on an analog multimeter used to adjust the ohmmeter circuit to compensate for variations in internal battery voltage.

Autoranging

A feature of some digital meters that automatically identifies the range of the signal and places the decimal point with the proper unit prefix.

Ammeter shunt

A resistor of a known small value inserted into a circuit to allow current measurement via voltage drop calculation using Ohm's law ($I = \frac{E}{R}$).

Clip-on ammeter

An ammeter that requires no physical connection to the circuit, using the electromagnetic field created by current flow to measure it.

Continuity test

A check performed to determine whether a current path is continuous, typically distinguishing between open, short, or closed circuits.

Open circuit

A circuit state characterized by infinite resistance where no current flows.

Short circuit

A circuit state with zero ohms of resistance where current flows without developing a voltage drop.

Closed circuit

A complete path for current flow with resistance values depending on the circuit components.

Full scale value

The maximum voltage or current value that a meter is designed to measure on its specific scale.

Nonlinear scale

A scale, such as the one found on an ohmmeter, where the spacing between divisions is not uniform and typically reads from right to left.