Meters

Question 1

What is an analog Meter

Answer 1

Pointer and scale indicates value
Common type of meter movement
D’arsonal movement
Often referred to as a moving-coil meter

Question 2

What does a rectifier do

Answer 2

Changes AC voltage to DC voltage

Question 3

What is a voltmeter

Answer 3

Designed to be connected directly across the source of power

Question 4

Voltmeter- Calculating the resistor value

Answer 4

Operating characteristics of the meter must be known

Full Scale values of the meter
- Meter requires a current of 50 mA and a voltage of 1 V to deflect the pointer full scale

Question 5

What is a Multi range Voltmeter

Answer 5

Designed to use one meter movement to measure several ranges of voltage

Calculating the resistor values

• values of four resistors shown can be determined using ohms law

Question 6

Parallax effect

Answer 6

Viewing angle will effect reading

Question 7

3 steps to reading a Voltmeter

Answer 7

1. Determine what the meter indicates
2. Determine the full scale value of the meter
3. Read the meter

Question 8

The Ammeter
What is it used for and how is it used

Answer 8

Used to measure current

Must be connected in series with the load to permit the load to limit current flow

Question 9

What is a Shunt

Answer 9

A shunt is used to set the value of an ammeter

Question 10

What is a MULTI range ammeter

Answer 10

Operate on more than one range
Done by connecting the meter movements to different shunts

Care must be taken so the shunt is never disconnected from the meter

Question 11

What is the Ayrton Shunt

Answer 11

Connects shunt to meter movement

Question 12

Why are shunts used with AC ammeters

Answer 12

To increase their range

Cannot be used to decrease their range
Most use a current transformer instead of

Question 13

What is a clamp on ammeter

Answer 13

Meter is clamped around one conductor supplying power to the load

Question 14

DC-AC clamp on ammeter

Answer 14

Most clamp on ammeters that have the ability to measure bother do not operate on current transformer principle

Question 15

What is the Hall Effect (DC-AC ammeters)

Answer 15

Basic principal of operation

Question 16

What is the ohmmeter

Answer 16

Used to measure resistance
Common VOM (volt-ohm-milliammeter) contains an ohmmeter

Basics types of analog ohmmeters: series and shunt

Question 17

What does ohmmeter measure

Answer 17

Voltage drop accross a resistor
Never to be connected to a circuit if power is on

Question 18

What is the low impedance voltage tester

Answer 18

Very large current draw compared to other types of voltmeters

Should never be used to test low power circuits

Question 19

What is an oscilloscope

Answer 19

Is a voltmeter
Measure voltage during a period of time
Produces a two dimensional image

Voltage range selection - voltage and time base

Question 20

4 oscilloscope considerations

Answer 20

Measuring frequency
Attenuated probes
Controls
Interpreting waveforms

Question 21

What is the wattmeter

Answer 21

Used to measure power in a circuit

Question 22

What are the two types of wattmeter

Answer 22

Dynamic and electronic

Question 23

What is a recording meter

Answer 23

Record an electrical value over a long period of time

Produces a graph of metered values

Detect spike voltages, currents of short duration, or sudden drops in voltage, current, or power

Question 24

What is a bridge circuit

Answer 24

Used to measure values of resistance, inductance, and capacitance accurately