Basic Electricity

The symbol for voltage is:

A or I

V or E

W

R

Correct! Wrong!

The symbol for current is:

A or I

V or E

W

R

Correct! Wrong!

The concept of electron flow on a conductor can best be described as:

wattage

current

resistance

voltage

Correct! Wrong!

Resistance can best be described as:

speed of flow of electrons

electrical pressure

flow of electrons through a circuit

opposition to flow of electrons (current)

Correct! Wrong!

Voltage can best be described as:

electrical pressure

resistance

flow of electrons through a circuit

speed of flow of electrons

Correct! Wrong!

Choose the best conductor from the list below.

cooper

steel

brass

aluminum

Correct! Wrong!

Choose a good semi-conductor from the list below.

steel

silicon

lead

plastic

Correct! Wrong!

The magnetic force which exists between any two objects that are similarly charged is:

weak

strong

one of repulsion

one of attraction

Correct! Wrong!

The magnetic force which exists between any two objects that are oppositely charged is:

weak

strong

one of repulsion

one of attraction

Correct! Wrong!

A lead-acid storage battery is an example of which method of producing electricity?

chemical

friction

light

pressure

Correct! Wrong!

An alternator or a generator, would be good examples of which method of producing electricity?

induced

friction

chemical

pressure

Correct! Wrong!

A good example of mutual induction in an automobile electrical system is:

coil

battery

headlight switch

starter solenoid

Correct! Wrong!

The state of the tail light switch shown, is such that one of the following terms could be applied to this circuit.

closed circuit

short circuit

series circuit

open circuit

Show hint

Correct! Wrong!

Which of the following is closer to the description of a series circuit?

devices connected with a break at a control device

devices connected to form only one current path

devices connected to form more than one path for current flow

devices connected to have a common voltage

Correct! Wrong!

Calculate the total resistance of a circuit that has three resistors: 60 ohms, 60 ohms and 15 ohms, all connected in parallel.

45 ohms

10 ohms

135 ohms

105 ohms

Correct! Wrong!

Calculate the current flowing in a circuit if the load is three resistors of 150 ohms, 450 ohms, and 120 ohms, connected in series to a 24 volt supply.

887A

0.0333A

0.413A

0.333A

Correct! Wrong!

If the supply voltage is 12 volts, the current flow is 8 amps what is the resistance?

.66 ohms

1.5 ohms

96 ohms

none of the above

Correct! Wrong!

Load devices are normally connected in parallel so that:

they can all be rated the same current rating

they can all be given the same fuse rating

they need not be fused

they can all be operated at independent current ratings

Correct! Wrong!

Which of the following correctly represents the magnetic laws of attraction and repulsion?

like poles repel, unlike poles repel

like poles repel, unlike poles attract

like poles attract, unlike poles repel

none of the above

Correct! Wrong!

Relays and solenoids all depend upon the principle of:

electrostatics

permanent magnetism

interaction

electromagnetism

Correct! Wrong!

The magnetic field (EMF) that is found near a current-carrying conductor moves:

only at the battery terminals

through the conductor

along the conductor

around the conductor in a circular way

Correct! Wrong!

The rule that determines the direction of the magnetic field of a current-carrying conductor is:

the rule of thumb

the three left hand rule

the three finger right hand rule

the right hand rule

Correct! Wrong!

How can a current-carrying wire be used to form a practical electromagnet?

twist the wire together

leave the wire as it is

wind a number of loops in alternate directions

wind a number of loops in the same direction

Correct! Wrong!

What advantage do electromagnets have over permanent magnets?

electromagnets are easily constructed

electromagnets do not use as much power as permanent magnets

electromagnets are easily controlled

none of the above.

Correct! Wrong!

What determines the polarity of an electromagnet?

the polarity of the power source

the amount of current

the gauge of wire used

the core material

Correct! Wrong!

Two coils are wound in the same direction each with the same number of turns, and are connected to the same source. One coil has an air core and the other an iron core. The iron core causes:

no change in the magnetic field

an increase in the density of the magnetic field

a decrease in the density of the magnetic field

magnetic saturation to occur

Correct! Wrong!

To identify an electrical meter which is to be used to measure resistance, the meter face will be marked:

ammeter

wattmeter

ohmmeter

voltmeter

Correct! Wrong!

A milli volt is:

1/1,000 v

1/1,000,000 v

1,000 v

1,000,000 v

Correct! Wrong!

Basic ammeters are connected in ________________ with the circuit.

series

parallel

series parallel

a shunt

Correct! Wrong!

To correctly measure the potential difference across a resistor in a circuit, a voltmeter is connected:

in parallel with the resistor-supply off

in parallel with the resistor-supply on

in series with the resistor-supply on

in series with the resistor-supply off

Correct! Wrong!

Calculate the value of the wattage in an engine''s block heater circuit if the ohmmeter reads 16.0 ohms and the voltmeter reads 120 volts.

900 W

400 W

1920 W

7.5 W

Correct! Wrong!

1. Magnets can cause electrons to flow in a conductor. 2. Electron flow in a conductor can produce magnetism. Of these two statements

both are false

both are true

the first is true; the second is false

the first is false; the second is true

Correct! Wrong!

A dim light on a vehicle may be caused by a high resistance circuit.

true

false

Correct! Wrong!

Higher than expected voltage drop in a circuit may be caused by:

6 volts batteries

in correct fuse rating

poor connections

soldered and sealed connections

Correct! Wrong!

Each resistor in a series circuit will cause a ___________ drop across itself.

wattage

voltage

amperage

resistance

Correct! Wrong!

The voltage drop across resistors in a basic parallel circuit will ______________ the battery voltage.

be equal to

be one-half

reduce

increase

Correct! Wrong!

37 An electromagnet''s strength may be increased by:

be equal to

be one-half

reduce

increase

Correct! Wrong!

If resistance is doubled and the voltage remains the same:

current will remain the same

electromotive force will be cut in half

current flow will double

current flow will be cut in half

Correct! Wrong!

While testing a solenoid coil, an ohmmeter reads an infinite or O.L. reading on the auto range setting. What is likely to be problem?

Short to ground

Shorted

Grounded

Open

Correct! Wrong!

A single clearance light in a circuit glows dimly. A technician connects a test light to the bulb socket terminal and the test light burns at normal brightness. What is likely to be the problem?

a bad ground to frame at the light could be the cause.

high resistance in the circuit from the battery to the light could be the cause.

the test light uses less amperage and therefore, glows brighter.

the wiring from the light switch was sized too small and is creating high resistance.

Correct! Wrong!

On a vehicle with a 12-volt system, a switched circuit feeds a pair of 50-watt auxiliary lights. What size of fuse would be required to protect the circuit and provide a 15% cushion for surges?

5 amp fuse

10 amp fuse

15 amp fuse

15 amp circuit breaker

Correct! Wrong!

A non-computerized vehicle''s oil pressure warning light fails to come on, even when the engine is shut down. All of the following are possible causes of the problem EXCEPT a:

defective sending unit

grounded wire from the light to the sending unit

high-resistance connection between the sending unit and the wiring coming from the warning lamp.

burn-out warning lamp bulb.

Correct! Wrong!

The blower motor in a truck is running very slowly. An ammeter shows a low current flow. This could be caused by:

high resistance in the circuit

low resistance in the circuit

an overcharged battery

a shorted blower motor

Correct! Wrong!

The taillight bulbs are inoperative and the tail light fuse ia burned out. A 12-volt test light is installed in place of the fuse, the test light comes on, but the taillight bulb remains out. When the connector near the bulb is disconnected, the 12-volt test light remains on. What may be the problem?

the circuit may be grounded between the fuse and the disconnected connector.

the circuit may be open between the disconnected connector and the bulb.

the test light is connected to the wrong fuse socket.

the circuit cannot be tested by placing two bulbs in series.

Correct! Wrong!

Checks are being made to determine the cause of a battery going dead after a few days when the equipment is sitting. Which of these statements is most correct?

a parasitic current draw of 2 amps could cause the battery to discharge.

two amps is a normal draw for a vehicle with an electronic control module.

a battery night switch with high internal resistance could be the cause.

corrosion at the battery cables would cause the batteries to drain.

Correct! Wrong!

When the driver''s door of the vehicle is opened, the interior lights illuminate, but dimly. The problem is most likely to be:

the headlight switch may be faulty.

a grounding problem to the door jam switch may be the cause.

the variable resister on the headlight switch is adjusted too low.

the light bulb is starting to fail and is growing more dim as a result.

Correct! Wrong!

When stalling new bulbs into sockets, a good idea to prevent possible corrosion of the contact surfaces by:

cleaning all the surfaces with a wire brush to provide better contact.

coating the surfaces with paint or some other sealant to keep out the air.

coating the prongs and base of a new bulb with dielectric grease.

coating the prongs and base of a new bulb with chassis grease.

Correct! Wrong!

A problem is encountered with the interior cab lights of a truck. When the bulb is out of the socket and the fuse is in place, everything is fine except the light does not work. Every time that a courtesy light bulb is replaced, the 15 amp fuse protecting that circuit burns out after a few seconds. What is the likely cause?

this could be caused by a short upstream (toward source voltage) from the light.

this could be caused by short downstream (toward circuit ground) from the respective light.

the interior light circuit is overloaded, and the bulb trips the fuse

the 15 amp fuse should be replaced with a 20 amp fuse

Correct! Wrong!

In the figure below, if the clearance light switch failed, what would happen in the circuit?

relay #1 and relay #2 would not be energized

the stoplights will fail to operate

the trailer clearance lights are not affected

the truck clearance lights are not affected

Show hint

Correct! Wrong!

In the figure below, the backup light circuit fuse keeps blowing. Technician A uses an ohmmeter to check the circuit across the backup light fuse contacts. Technician B uses an ammeter to check the circuit across the backup light fuse contacts. Who is right?

A only

B only

Both A and B

Neither A nor B

Show hint

Correct! Wrong!

The symbol for voltage is:

The symbol for current is:

The concept of electron flow on a conductor can best be described as:

Resistance can best be described as:

Voltage can best be described as:

Choose the best conductor from the list below.

Choose a good semi-conductor from the list below.

The magnetic force which exists between any two objects that are similarly charged is:

The magnetic force which exists between any two objects that are oppositely charged is:

A lead-acid storage battery is an example of which method of producing electricity?

An alternator or a generator, would be good examples of which method of producing electricity?

A good example of mutual induction in an automobile electrical system is:

The state of the tail light switch shown, is such that one of the following terms could be applied to this circuit.

Which of the following is closer to the description of a series circuit?

Calculate the total resistance of a circuit that has three resistors: 60 ohms, 60 ohms and 15 ohms, all connected in parallel.

Calculate the current flowing in a circuit if the load is three resistors of 150 ohms, 450 ohms, and 120 ohms, connected in series to a 24 volt supply.

If the supply voltage is 12 volts, the current flow is 8 amps what is the resistance?

Load devices are normally connected in parallel so that:

Which of the following correctly represents the magnetic laws of attraction and repulsion?

Relays and solenoids all depend upon the principle of:

The magnetic field (EMF) that is found near a current-carrying conductor moves:

The rule that determines the direction of the magnetic field of a current-carrying conductor is:

How can a current-carrying wire be used to form a practical electromagnet?

What advantage do electromagnets have over permanent magnets?

What determines the polarity of an electromagnet?

Two coils are wound in the same direction each with the same number of turns, and are connected to the same source. One coil has an air core and the other an iron core. The iron core causes:

To identify an electrical meter which is to be used to measure resistance, the meter face will be marked:

A milli volt is:

Basic ammeters are connected in ________________ with the circuit.

To correctly measure the potential difference across a resistor in a circuit, a voltmeter is connected:

Calculate the value of the wattage in an engine''s block heater circuit if the ohmmeter reads 16.0 ohms and the voltmeter reads 120 volts.

1. Magnets can cause electrons to flow in a conductor. 2. Electron flow in a conductor can produce magnetism. Of these two statements

A dim light on a vehicle may be caused by a high resistance circuit.

Higher than expected voltage drop in a circuit may be caused by:

Each resistor in a series circuit will cause a ___________ drop across itself.

The voltage drop across resistors in a basic parallel circuit will ______________ the battery voltage.

37 An electromagnet''s strength may be increased by:

If resistance is doubled and the voltage remains the same:

While testing a solenoid coil, an ohmmeter reads an infinite or O.L. reading on the auto range setting. What is likely to be problem?

A single clearance light in a circuit glows dimly. A technician connects a test light to the bulb socket terminal and the test light burns at normal brightness. What is likely to be the problem?

On a vehicle with a 12-volt system, a switched circuit feeds a pair of 50-watt auxiliary lights. What size of fuse would be required to protect the circuit and provide a 15% cushion for surges?

A non-computerized vehicle''s oil pressure warning light fails to come on, even when the engine is shut down. All of the following are possible causes of the problem EXCEPT a:

The blower motor in a truck is running very slowly. An ammeter shows a low current flow. This could be caused by:

Checks are being made to determine the cause of a battery going dead after a few days when the equipment is sitting. Which of these statements is most correct?

When the driver''s door of the vehicle is opened, the interior lights illuminate, but dimly. The problem is most likely to be:

When stalling new bulbs into sockets, a good idea to prevent possible corrosion of the contact surfaces by:

In the figure below, if the clearance light switch failed, what would happen in the circuit?

In the figure below, the backup light circuit fuse keeps blowing. Technician A uses an ohmmeter to check the circuit across the backup light fuse contacts. Technician B uses an ammeter to check the circuit across the backup light fuse contacts. Who is right?

Success!

Heavy-Duty Mechanic - Trucks & Equipment