# Electrical Unit: Ultimate Practice Exam! Quiz

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Are you preparing for an upcoming electrical unit exam? This quiz can serve as the preparation for the exam. As far as this quiz goes, you will see what the traditional automobile battery type is, which battery has removable cell covers, what a technician must always wear when working with a battery, and standard automotive network configurations. This enthralling quiz will help you study for the exam. Good luck.

• 1.

### _____________ is/are fundamental to the automobile.

• A.

A 12-volt storage battery

• B.

An engine starting system

• C.

A charging system

• D.

All of the above

D. All of the above
Explanation
Are of the listed are important for a modern automobile.

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• 2.

### The traditional automobile battery type is the:

• A.

• B.

Ion.

• C.

Helium.

• D.

Nitrogen.

Explanation
Lead plates and acid are the two main parts of a car battery.

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• 3.

### The nominal voltage of each cell of a battery is _____________ volts.

• A.

1.9

• B.

2.0

• C.

2.1

• D.

2.2

C. 2.1
Explanation
Each healthy cell in a car's battery should have 2.1 volts. 6 cells multiplied by 2.1 equals 12.6 volts.

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• 4.

### The following battery has removable cell covers.

• A.

Sealed

• B.

Maintenance free

• C.

• D.

None of the above

Explanation
Only the flooded cell battery has removable covers to check the internal water level.

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• 5.

### A technician must always wear ______________ when working on a battery.

• A.

Designer clothes

• B.

Earrings

• C.

Tennis shoes

• D.

Safety glasses

D. Safety glasses
Explanation
You always wear safety glasses when working in the shop, on anything.

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• 6.

### Tech A says that batteries should be disposed of in landfills. Tech B says that batteries must be recycled. Who is correct?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

B. Tech B
Explanation
Car batteries have lead and should always be recycled.

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• 7.

### Tech A says that the starter converts mechanical energy to electrical energy. Tech B says that the starter converts electrical energy to mechanical energy. Who is correct?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

B. Tech B
Explanation
The starter takes the battery's charge and converts it into movement, or mechanical energy.

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• 8.

### Tech A says that the alternator converts electrical energy into mechanical energy. Tech B says that the alternator converts mechanical energy into electrical energy. Who is correct?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

A. Tech A
Explanation
The alternator converts the movement of the engine into electrical, AC volt energy, then rectifies that into DC voltage.

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• 9.

### The _____________ monitors battery voltage and varies current flow through the rotor field circuit.

• A.

Slip rings

• B.

Rotor

• C.

Voltage regulator

• D.

Armature

C. Voltage regulator
Explanation
The voltage regulator monitors voltage and makes adjustments based upon demand and use of the vehicle's electrical system.

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• 10.

### The process of converting alternating current (AC) into direct current (DC) is called:

• A.

Rectification.

• B.

Electromotive force (EMF).

• C.

Counter-electromotive force (CEMF).

• D.

Recertification.

A. Rectification.
Explanation
The alternator rectifies the AC voltage into DC voltage.

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• 11.

### The ______________ allows current to flow one way in the rectifier assembly.

• A.

Diode

• B.

Thyroid

• C.

Electromotive force (EMF)

• D.

Counter-electromotive force (CEMF)

A. Diode
Explanation
The diode only allows current to flow one way through the circuit.

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• 12.

### Tech A says that to do a quick test on an alternator charging system is to remove one of the cables off the battery posts, and if the engine continues to run, then the charging system is good. Tech B says that the practice of removing a battery cable connection can damage the electronics on the vehicle. Who is correct?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

B. Tech B
Explanation
Removing the battery cable from the battery is an antiquated method of testing the charging system. The alternator needs to be taxed and the current observed to truly know if it is faulty.

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• 13.

### On modern vehicles, what replaced the voltage regulator?

• A.

Power train control module (PCM) or body control module (BCM)

• B.

Electronic control module (ECM)

• C.

Electromotive force (EMF)

• D.

Counter-electromotive force (CEMF)

A. Power train control module (PCM) or body control module (BCM)
Explanation
Control modules are now responsible for monitoring and adjusting current output of an alternator.

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• 14.

### Tech A says that the standard 12-volt car battery has 3 cells with 4.2 volts in each cell. Tech B says that the standard 12-volt car battery has 4 cells with 3.3 volts each. Who is correct?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

D. Neither Tech A nor B
Explanation
The standard car battery has 6 cells with 2.1 volts a piece.

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• 15.

### Tech A says that failure of a battery hold down can cause battery plate damage. Tech B says that a bungee cord is a suitable battery hold down. Who is correct?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

A. Tech A
Explanation
The constant jarring of the battery internals will cause the lead plates to shatter. Anything other than an acceptable battery hold down is insufficient.

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• 16.

### CAN-bus is a _______-speed network.

• A.

Medium

• B.

High

• C.

Low

• D.

None of the above

B. High
Explanation
Data on a CAN transmits at a high speed.

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• 17.

### Some networks transmit and receive signals over a single wire, but most have dual wires and are commonly called “CAN-bus high (H)” and “CAN-bus low (L),” with the same message sent on both lines.

• A.

True

• B.

False

A. True
Explanation
There are some situations where there is a single wire, but most networks operate on a two wire system, and the data is transmitted at two different speeds.

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• 18.

### All of the following are common automotive network configurations EXCEPT:

• A.

Bussed parallel.

• B.

Looped series.

• C.

Star parallel.

• D.

Triangle series.

D. Triangle series.
Explanation
CANs can not exist in the shape of a triangle.

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• 19.

### Which of the following is not a diagnostic tool used in the testing of the controlled area network bus (CAN-bus) system?

• A.

Data link connector (DLC) breakout box

• B.

Digital volt-ohmmeter

• C.

Network converter

• D.

Digital storage oscilloscope

C. Network converter
Explanation
The breakout box, DVOM, and oscilloscope are all options in diagnosing a CAN.

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• 20.

### Which of the following may be required when diagnosing and repairing a vehicle's electronic modules?

• A.

Software transfers

• B.

Flash reprogramming

• C.

• D.

All of the above

D. All of the above
Explanation
Software updates, transfers, and reprogramming may all need to be performed when diagnosing or replacing a vehicle's control module.

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• 21.

### The horn switch is usually mounted in the steering wheel and requires a method to maintain an electrical connection to the circuit as the steering wheel rotates. This connection is called a:

• A.

Slot spring.

• B.

Swivel switch.

• C.

Clock spring.

• D.

Diaphragm.

C. Clock spring.
Explanation
The clock spring is the part the links the steering wheel electrical functions to the rest of the car.

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• 22.

### If only the intermittent speed setting on the windshield wipers is not working, it may be caused by a faulty:

• A.

Fuse.

• B.

Delay module.

• C.

Motor brush.

• D.

Switch.

B. Delay module.
Explanation
The delay module is the only thing listed that will effect the intermittent wiper operation.

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• 23.

### Tech A says higher-speed networks are used for critical data such as supplemental restraint systems, anti-lock brake systems, and engine controls. Tech B says lower-speed networks are used for lower priority data such as data related to entertainment systems. Who is correct?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

C. Both Techs A and B
Explanation
We want to use a higher speed to transfer the most important data.

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• 24.

### Tech A says the CAN-bus system has a data link connector (DLC) that provides a connection into the data network and allows scan tools to connect into the network. Tech B says when there is an issue with the CAN-bus system, a diagnostic trouble code (DTC) with an “N” designation will typically be set, indicating the nature of the fault. Who is correct?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

A. Tech A
Explanation
The DLC is the interface between the vehicle's systems and the scan tool. U is the generic letter designation for communication faults.

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• 25.

### Tech A says that the horn circuit can fail in many ways. Any of the components in the circuit can go bad, as can the wiring. Tech B says when testing the horn, it may be easiest to first see if power is getting to the horn when it is activated, because it is not uncommon for horns to go bad, especially if they are rarely used or overused. Who is correct?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

C. Both Techs A and B
Explanation
Anything or multiple things can go wring in an electrical circuit. Horns can go bad if rarely used or overused. Testing for power supply and ground at the horn is an easy way to test its health.

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• 26.

### What does DVOM stand for?

• A.

Digital voltâ€“hour meter

• B.

Digital volt-ohmmeter

• C.

Digital valve ohmmeter

• D.

Digital variable oval meter

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

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• 27.

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

• A.

2168 millivolts.

• B.

2.168 volts.

• C.

1000 mV.

• D.

Both A and B

D. Both A and B
Explanation
2168mV = 2.168 volts = 2168millivolts

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• 28.

### When probing wires, you should do all these EXCEPT:

• A.

Back probe when possible.

• B.

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

• C.

Reinsulate the hole with room temperature vulcanizing silicone.

• D.

Never use excessive force.

C. Reinsulate the hole with room temperature vulcanizing silicone.
Explanation
Never reseal a hole after probing with silicone.

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• 29.

### 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?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

D. Neither Tech A nor B
Explanation
Most meters can't handle that much current and before measuring current, you should check the DVOM to see what it can handle. Amperage or current is measured with a clamp.

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• 30.

### 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?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

C. Both Techs A and B
Explanation
DVOMs have both a manual and auto setting. OL does mean you are measuring more than the maximum setting set on the meter.

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• 31.

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

• A.

12 volts

• B.

9.3 volts

• C.

8.3 volts

• D.

3.7 volts

B. 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 voltage going to the load is 9.3 volts.

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• 32.

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

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

C. Both Techs A and B
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.

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• 33.

### 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?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

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

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• 34.

### 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?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

A. Tech A
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.

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• 35.

### 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?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

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

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• 36.

### 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:

• A.

12 amps.

• B.

1.2 amps.

• C.

0.12 amps.

• D.

0.012 amps.

C. 0.12 amps.
Explanation
Solve for ohms law. V=IR

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• 37.

### 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?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

C. Both Techs A and B
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.

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• 38.

### 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?

• A.

1

• B.

10

• C.

100

• D.

10000

C. 100
Explanation
Solve for ohms law. V=IR

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• 39.

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

• A.

Select auto range volts DC.

• B.

Connect the red lead to volt/ohm.

• C.

Remove the positive battery cable.

• D.

Ensure the current is flowing.

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

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• 40.

### 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?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

C. Both Techs A and B
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.

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• 41.

### 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?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

C. Both Techs A and B
Explanation
You need current flow to measure a drop in voltage, and can be done across any kind of circuit or load.

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• 42.

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

• A.

Divide the total current flow by the volts.

• B.

Multiply the current flow by 4.

• C.

Add the current flow for each resistor together.

• D.

Subtract the volts from amps and add 2 volts.

C. Add the current flow for each resistor together.
Explanation
The sum of the resistances in a parallel circuit equals the total current flow in the circuit.

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• 43.

### A variable resistor:

• A.

Has a fixed resistance.

• B.

Changes with the amount of voltage applied.

• C.

Has a movable arm that swipes across a coil that has less resistance at one end and more at the other.

• D.

All of the above

C. Has a movable arm that swipes across a coil that has less resistance at one end and more at the other.
Explanation
Think of a fuel level sensor, also known as a sending unit.

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• 44.

### 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?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

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

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• 45.

### 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?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

A. Tech A
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.

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• 46.

### Tech A says an atom with more electrons than protons has an overall positive charge. Tech B says not all atoms can give up or accept electrons easily. Who is correct?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

B. Tech B
Explanation
The charge of electrons and protons in an atom cancel each other. Some atoms are already "happy", others want to accept electrons, and others what to give up theirs to have 8 valence electrons.

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• 47.

### What materials make a good insulator?

• A.

Copper and aluminum

• B.

Ceramic and plastic

• C.

Both A and B

• D.

None of the above

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

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• 48.

### Tech A says a resistor is a component designed to extract energy from the current flow. Tech B says he uses a voltmeter to check for a voltage drop. Who is correct?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

C. Both Techs A and B
Explanation
Resistors or loads eat up the energy from the source. A voltmeter is used to measure the drop of voltage through a circuit.

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• 49.

### Tech A says you must have power supply for a simple circuit to work. Tech B says a switch will interrupt. Who is correct?

• A.

Tech A

• B.

Tech B

• C.

Both Techs A and B

• D.

Neither Tech A nor B

C. Both Techs A and B
Explanation
The power supply is one of the components of a simple circuit. The switch interrupts the current in a circuit.

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• 50.

### Volts, amps, and ohms are the three basic units of electrical measurement.

• A.

True

• B.

False

A. True
Explanation
Voltage, amperage, and resistance are the 3 main electrical measurements.

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• Current Version
• Mar 21, 2023
Quiz Edited by
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• Jan 23, 2015
Quiz Created by
Atahcpss

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