Multimeter quiz

Multimeter components

-Boots -Probes/leads -Multimeter -USB connector -Temp probs (if so equipped) Multimeters are really several measuring devices put into one

Probes should be

-Handled with care -Stored when not in use -Handle the probes like you would handle electric wire

Analog multimeter is/can

-Making infinite amount of readings -prone to interpretation errors -requires effort to make and interpret readings

The three types of jeweled bearings

-Ring and End Stone -Spring-back -V-Jewel bearing V-jewel bearing is most common

6 main parts of a multimeter

-Scale -Pointer -Meter movement -Function Switch -Meter Leads -Meter Lead ports

Digital Multimeter is/can

-capable of making a finite amount of possible indications -easy to operate -rugged design -not subject to interpretation errors

Name two types of meter movements

1) D'arsonval movement 2) Weston movement

Name two types of multimeter bearings

1) Jeweled 2) Taut band (almost zero friction)

3 desired characteristics of an analog multimeter

1) frictionless movements 2) Ability to measure very large and very small values 3) Minimum circuit loading

Analog multimeters

1) works on principles kd the galvnomater - magnetism 2) interaction of 2 magnetic fields

The most common digit or count display is

3 1/2 digit or count This means the display can read 0-9 on the whole count and 1 or blank on the 1/2 count

Analog meter movements

A coil of very fine wire is mounted and pivoted so that i can rotate in a magnetic field of a permanent magnet

Galvanometer

A magnetized needle suspended within the coil of a wire Reacts to minute electromagnetic influences caused within itself by a flow of small current current flow in the coil of wire produces mag field and the ,magnetized needle tries to align itself with it

What is a shunt?

A shunt is a resistor that is in series with the multimeters leads that increases the range of a multimeter when measuring current

Wether you are measuring current, voltage, resistance, or power, the electric measuring device is

Actually reading some amount of current that is being taken from circuit under test

2 types of multimeters

Analog and digital

Multimeter measures

Current: DC and AC Voltage: AC (mVAC-600VAC) and DC (mVDC-600 VDC0) Resistance: mOhms-50Mohms

Electrical measuring equipment

Equipment is primarily based on electromagnetism

What is a multiplier in a multimeter?

It is a resistor that is in series and increases a meters range when measuring voltage

Digital multimeters operate off of

Microprocessing-Input, decision , memory, output

All parts of analog multimeter

Pointer, insulator, moving coil, movement frame, band anchor, tension spring, 2 taut-band suspension, solder terminal, Iron core, balance weight, and top bridge

Amp meters use

Shunts as calibrated resistance placed in parallel with leads to extend usefulness of multimeter when measuring current

How galvanometer works (pt 2)

The amount of pointer deflection is proportional to the amount of current flowing through the coil Current flowing in the coil creates a mag field that reacts with the magnetic field created by the permanent magnet force of attraction/repulsion causes moving coil to deflect pointer connected to moving coil deflects and is read against a scale

The terms and bits are used to describe

a meters resolution

Analog meters are needed to measure small currents because

analog meters are sometimes very sensitive and only require .00005 amps to produce full-scale deflection

Pivot bearings on analog multimeter should be?

as frictionless as possible because of the sensitivity, this is accomplished by using jeweled bearings

(volt meter) Circuits maybe tested while hot but

care must be taken in order to avoid shorting, that is metal touching between ground and terminal

Pivoted bearing has been replaced by a

coil suspended on a taut platinum -iridium band held by spring tension in the instrument frame

What can damage analog multimeter?

dropping, throwing, shocking, vibration, etc

Shunt resistance is also known as (ammeter)

instrument shunt

Volt/ohm meter uses

multipliers as a calibrated resistance to extend useful range of multimeter

Resolution on a multimeter

refers to how small the DMM can make

A volt meter with moving coil, measures flow through instrument but

since the voltage is directly proportional to current, the meter dial is marked on volts

Sensitivity in a analog multimeter is determined by?

the amount of current required to produce a full scale deflection of the indicating needle

Taut-band movement:

the problems of pivoted bearings has been overcome

Iron core is used for what in analog multimeter?

used to provide a uniform field