Quiz On Meter Usage And Circuit Diagnosis

1. What does DVOM stand for?

Digital volt–hour meter

Digital volt-ohmmeter

Digital valve ohmmeter

Digital variable oval meter

A DVOM is a digital volt-ohmmeter and is has that name because of what it tests and how it displays the measurement.

Explanation

A DVOM is a digital volt-ohmmeter and is has that name because of what it tests and how it displays the measurement.

2. When discussing a circuit, you know the voltage is 0.202 volts and the current draw is 0.00202 amp. What is the resistance in the circuit?

1

10

100

10000

Solve for ohms law. V=IR

Explanation

Solve for ohms law. V=IR

3. When doing a voltage drop test, you should do all these EXCEPT:

Select auto range volts DC.

Connect the red lead to volt/ohm.

Remove the positive battery cable.

Ensure the current is flowing.

If you're doing a voltage drop, you need the circuit to be live. Disconnecting the battery cable will open the circuit.

Explanation

If you're doing a voltage drop, you need the circuit to be live. Disconnecting the battery cable will open the circuit.

4. When doing a voltage drop test, the reading is 2.7 volts across the circuit. How many volts are going to the load?

12 volts

9.3 volts

8.3 volts

3.7 volts

The voltage drop test measures the difference in voltage across a circuit. In this case, the reading is 2.7 volts. Since the total voltage in the circuit is 12 volts, subtracting the voltage drop from the total voltage gives us the voltage going to the load. Therefore, the volts going to the load would be 12 volts - 2.7 volts = 9.3 volts.

Explanation

The voltage drop test measures the difference in voltage across a circuit. In this case, the reading is 2.7 volts. Since the total voltage in the circuit is 12 volts, subtracting the voltage drop from the total voltage gives us the voltage going to the load. Therefore, the volts going to the load would be 12 volts - 2.7 volts = 9.3 volts.

5. Tech A says there are three ways to check a circuit with Ohm's law. Tech B says if you know two of the measurements, Ohm's law will show you the third. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

You can check a circuit for resistance, voltage, and current. If you have two of the measurements, you will be solving for a single variable.

Explanation

You can check a circuit for resistance, voltage, and current. If you have two of the measurements, you will be solving for a single variable.

6. Tech A says relays are turned on and off by a small amount of current. Tech B says there are two types of relays: normally closed (NC) and normally open (NO) types. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

A small amount of current is used to energize the windings in a relay. They can either be normally open or closed.

Explanation

A small amount of current is used to energize the windings in a relay. They can either be normally open or closed.

7. A variable resistor:

Has a fixed resistance.

Changes with the amount of voltage applied.

All of the above

Think of a fuel level sensor, also known as a sending unit.

Explanation

Think of a fuel level sensor, also known as a sending unit.

8. Tech A says voltage drops can be measured as long as current is flowing. Tech B says voltage drops can be measured across components, connectors, or cables. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

You need current flow to measure a drop in voltage, and can be done across any kind of circuit or load.

Explanation

You need current flow to measure a drop in voltage, and can be done across any kind of circuit or load.

9. When calculating current flow in a parallel circuit that has 4 resistors, you would:

Divide the total current flow by the volts.

Multiply the current flow by 4.

Add the current flow for each resistor together.

Subtract the volts from amps and add 2 volts.

The sum of the resistances in a parallel circuit equals the total current flow in the circuit.

Explanation

The sum of the resistances in a parallel circuit equals the total current flow in the circuit.

10. What materials make a good insulator?

Copper and aluminum

Ceramic and plastic

Both A and B

None of the above

Ceramics, plastics and rubbers are good insulators. They do not readily accept or give electrons.

Explanation

Ceramics, plastics and rubbers are good insulators. They do not readily accept or give electrons.

11. Tech A says an oscilloscope is commonly referred to as a lab scope or just scope. Tech B says lab scopes are not very important test instruments in a modern automobile. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

Yes, the scope is commonly referred to as either of the three listed, and are very important instruments in testing and inspecting faults with modern automobiles.

Explanation

Yes, the scope is commonly referred to as either of the three listed, and are very important instruments in testing and inspecting faults with modern automobiles.

12. Tech A says Ohm's law will show how many amps are needed in a circuit with 110 ohm resistor and a 12-volt power supply. The amps needed are:

12 amps.

1.2 amps.

0.12 amps.

0.012 amps.

Solve for ohms law. V=IR

Explanation

Solve for ohms law. V=IR

13. Tech A says you can calculate total circuit current with this formula I = V ÷ R. Tech B says you can determine the total voltage drop using Ohm's law. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

Ohm's law is V=IR, no matter how you arrange it. You can use Ohm's law to determine the total drop of voltage.

Explanation

Ohm's law is V=IR, no matter how you arrange it. You can use Ohm's law to determine the total drop of voltage.

14. Tech A says most digital volt-ohmmeters (DVOMs) have both auto range and a manual range setting. Tech B says OL means overload and indicates the voltage being read is higher than the maximum. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

DVOMs have both a manual and auto setting. OL does mean you are measuring more than the maximum setting set on the meter.

Explanation

DVOMs have both a manual and auto setting. OL does mean you are measuring more than the maximum setting set on the meter.

15. Tech A says when doing a voltage drop test, the voltmeter needs to be set to ohm. Tech B says current has to be flowing to do a voltage drop test. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

DVOM needs to be set to test volts, and yes, you need a live circuit to test the voltage drop.

Explanation

DVOM needs to be set to test volts, and yes, you need a live circuit to test the voltage drop.

16. Tech A says when checking resistance in a circuit, you need to have power connected to the component. Tech B says ideally, you should have a component disconnected. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

A circuit does not need to be live to test for resistance. Having the component will keep from any feedback testing from happening.

Explanation

A circuit does not need to be live to test for resistance. Having the component will keep from any feedback testing from happening.

17. Tech A says checking a variable resistor is almost the same as a regular resistor. Tech B says you have to have a different type of digital volt-ohmmeter (DVOM) to read a variable resistor. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

A resistor is a resistor. There are only small differences between them. There is only one kind of DVOM.

Explanation

A resistor is a resistor. There are only small differences between them. There is only one kind of DVOM.

18. Tech A says that in a relay, current is sent through a resistor and a magnetic field is produced. Tech B says to check the amps in a circuit, you need to connect the leads parallel to the circuit. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

A relay has two sides. The control side has a winding that gets charged and closes the switch on the other side of the relay. To read amperage in a circuit, you either need an amp clamp or to hook up the DVOM in series with the circuit.

Explanation

A relay has two sides. The control side has a winding that gets charged and closes the switch on the other side of the relay. To read amperage in a circuit, you either need an amp clamp or to hook up the DVOM in series with the circuit.

19. Tech A says parallel circuits are like links in a chain. Tech B says total current in a parallel circuit equals the sum of the current flowing in each branch of the circuit. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

Parallel circuits are when the resistances are side by side, with individual power supplies and grounds. The sum of all of the current draws in a parallel circuit is the total current draw in the circuit.

Explanation

Parallel circuits are when the resistances are side by side, with individual power supplies and grounds. The sum of all of the current draws in a parallel circuit is the total current draw in the circuit.

20. When probing wires, you should do all these EXCEPT:

Back probe when possible.

Use caution when piercing wiring not to damage the wire internally.

Reinsulate the hole with room temperature vulcanizing silicone.

Never use excessive force.

Never reseal a hole after probing with silicone.

Explanation

Never reseal a hole after probing with silicone.

21. Tech A says high resistance causes an increase in current flow. Tech B says a voltage drop is another name for high resistance. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

High resistance does not increase current flow. Solve ohms law for constant voltage and infinite resistance. The drop of voltage in a circuit is a measurement of how much resistance there is in the part of the circuit being measured.

Explanation

High resistance does not increase current flow. Solve ohms law for constant voltage and infinite resistance. The drop of voltage in a circuit is a measurement of how much resistance there is in the part of the circuit being measured.

22. When reading a digital volt-ohmmeter (DVOM), you have a reading of 2168 mV, which is the same as:

2168 millivolts.

2.168 volts.

1000 mV.

Both A and B

2168mV = 2.168 volts = 2168millivolts

Explanation

2168mV = 2.168 volts = 2168millivolts

23. Tech A says testing across the battery will show you better voltage. Tech B says when checking across a switch, it has a 2-volt drop, which means only about 10 volts are going to the light. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

Testing from the battery directly will give you the best amount of voltage. The voltage drop is the difference of voltage in two different places in a circuit. What is left for the load is the drop amount, and its difference with battery voltage.

Explanation

Testing from the battery directly will give you the best amount of voltage. The voltage drop is the difference of voltage in two different places in a circuit. What is left for the load is the drop amount, and its difference with battery voltage.

24. Tech A says AC stands for alternating voltage. Tech B says DC is used in electric motors on most hybrid vehicles. Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

AC stands for alternating current. DC stands for direct current and is not used in hybrid vehicles to run electric motors.

Explanation

AC stands for alternating current. DC stands for direct current and is not used in hybrid vehicles to run electric motors.

25. Tech A says you can measure up to 100 amps directly through the meter. Tech B says when checking high volts, you need to use a volt clamp so you don't damage the digital volt-ohmmeter (DVOM). Who is correct?

Tech A

Tech B

Both Techs A and B

Neither Tech A nor B

Tech A claims that measuring up to 100 amps directly through a meter is possible, which is incorrect for standard DVOMs without a clamp adapter due to risk of damage. Tech B suggests using a "volt clamp" for high voltage measurements, a term misused, as voltage requires proper probes, not clamps. Both are incorrect.

Explanation

Tech A claims that measuring up to 100 amps directly through a meter is possible, which is incorrect for standard DVOMs without a clamp adapter due to risk of damage. Tech B suggests using a "volt clamp" for high voltage measurements, a term misused, as voltage requires proper probes, not clamps. Both are incorrect.