Line H Flashcards
which DMM function is used to measure resistance
?
Ohmmeter
which DMM function is used to measure current flow in an electrical circuit ?
Ammeter
What is the impedance value of most digital voltmeters?
10 Megaohms
which meters are more accurate : analog or digital?
Digital
which meter is more commonly used in the electrical trade: analogue or digital?
Digital
What does DMM stand for?
Digital Multimeter
which meter is uses to take current measurements without opening the circuit?
Clamp on Ammeter
Which of the two meter types, true RMS or average responding would be used by an electrician testing an electronic ballast in florescent lighting fixtures
True RMS DMM
When measuring the voltage across a component, will meter loading cause the meter reading to be higher or lower than the voltage across the component without the meter in the circuit
Lower
Which DMM setting would be used to measure the voltage output of an alternator?
A/C
Which DMM setting would be used to measure the voltage output of an Rectifier?
D/C
The source voltage of the circuit is 120 volts AC, and the resistance of the circuit is 10 ohms. what type of ammeter would you use to measure the current in the circuit?
clamp on 120/10 = 12A, DMM Max 10a
list two advantages of clamp on style of ammeter over a DMM
- Circuit does not have to be interrupted or deenergized to take a current measurement
- Able to measure currents in excess of 10A
which meter would be selected to provide quick and easy testing of whether the fuse is open or has a complete path through it?
The continuity function of a DMM
When using the diode test function to a silicon diode, if the diode is good , a DMM will display the _______?
The forward bias voltage drop
Which measurement function of a DMM requires an internal battery to provide current flow though the circuit
Resistance or Ohms
Analog meters are used over DMM style meters due to their superior accuracy
A) true
B) false
False
When testing for the potential of a set of series connected batteries, which function of the DMM would be used
A) Hold button
B) DC voltmeter
C) Continuity
D) AC voltmeter
DC Voltmeter
A DMM with an autoranging feature will automatically select the________ with the best accuracy and resolution for the measurement.
A) screen
B)range
C)dial setting
D)connection
range
What is the impedance of most digital voltmeters?
A) 2000 ohms
B) 10 megaohms
C) 10 milliohms
D) 2000 megaohms
10 Megaohms
Care should be taken that the ___________ function is never used on a live circuit
A) Ammeter
B) DC Voltmeter
C) Wattmeter
D) Ohmmeter
Ohmmeter
True RMS meters use an integrated circuit to ________ the RMS value of the waveform under test.
A) rectify
B) reduce
C) extend
D) compute
Compute
In order for a DMM to accurately measure the voltage of a variable speed drive a true RMS meter is required.
A)True B)False
True
Comparing a meter’s reading with a precisely accurate laboratory meter is called:
A)calibrating
B) parallaxing
C)standardizing
D)zeroing
Calibrating
What answer best reflects the position that the Digital multimeter can be used in.
A) vertically
B) horizontally
C) either horizontally or vertically
D) in any position
In any position
When using the ammeter function of a DMM, it is important to?
A)De-energize the circuit while taking readings.
B)Turn the function dial to the off position.
C)Confirm the meter is rated to handle the expected current.
D)add loops to the leads to increase the accuracy of your reading.
Confirm the meter is rated to handle the expected current
Most DMM’s have a wattmeter function.
1) True
2) False
false
What advantage(s) does a digital wattmeter have over an analog wattmeter?
1) No batteries required
2) Accuracy
3) Ease of use
4) all of the above
accuracy
A digital wattmeter takes current and voltage measurements electronically, thousands of times per second.
1) True
2) False
True
If you are not familiar with the use of a particular meter, you should:
1) Use heavy-duty leads.
2) Take the cover off first and inspect the mechanism.
3) Send it out for calibration.
4) Read the instruction booklet carefully.
Read the instruction booklet carefully
When using a digital wattmeter, you should always:
1) read the manufacturers instructions.
2) de-energize the circuit prior to making connections.
3) connect the current jacks in series with the circuit being tested.
4) Connect the voltage jacks in parallel with the circuit being tested.
5) All of the above.
All of the above
A digital wattmeter measures the_________consumed in an electrical circuit.
1) current
2) voltage
3) electrons
4) power
Power
A wattmeter is to be connected to a heating circuit. The resistance of the heater is 29.71 ohms. The source voltage is known to be 208v. The wattmeter is rated for 1500 watts and the fuse in it is rated for 10 amps. Can the wattmeter safely measure the power output of the heater?
1) Yes
2) No
3) Only if the fuse is rated for the voltage.
Yes
