Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Foundation > Basic Electricity 1 > Flashcards

Basic Electricity 1 Flashcards

1
Q

What are Free Electrons?

A

Free electrons are the electrons that can move around within an object. The greater the number of free electrons, the greater the object’s negative electric charge. Thus, the amount electric charge is a measure of free electrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are Valence Electrons?

A

Valence electrons are the electrons in the outermost shell. When external energy, such as heat, light, or electrical energy, act on certain materials, the electrons in the individual atoms gain energy, become excited, and may move to a higher energy level.

If enough energy acts on the atom, some of the valence electrons will leave the atom, as shown in the figure below. These electrons are free electrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The movement of free electrons do what in a metal conductor?

A

Provides electric current flow.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is proportional to an electrons energy level?

A

The energy level of an electron is proportional to its distance from the nucleus. Higher energy level electrons exist in orbits, or shells, that are farther away from the nucleus. These shells nest inside one another and surround the nucleus. The nucleus is the center of all the shells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the different amount of electrons you might find in the different electrons shells?

A

Each shell has a maximum number of electrons it can hold. For example, the K shell holds a maximum of two electrons and the L shell holds a maximum of eight electrons. As shown in the figure below, each shell has a specific number of electrons that it will hold for a particular atom.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the two rules concerning electron shells that make it possible to predict the electron distribution of any element?

A
  1. The maximum number of electrons that can fit in the outermost shell of any atom is eight.
  2. The maximum number of electrons that can fit in the next-to-outermost shell of any atom is 18.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are electrons in the outer most shell called?

  1. free electrons.
  2. positrons.
  3. valence electrons.
  4. K shell electrons.
A

3 Valence electrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is Electrostatic force?

A

The electron and the nucleus attract each other. Electrostatic force is the name of this attraction. Electrostatic force holds the electron in orbit. The lines in the figure below show this force.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why do charged objects repel or attract each other?

A

Charged objects repel or attract each other because of the way these electrostatic fields interact. When two objects of opposite charge are near one another, the electrostatic field is concentrated in the area between them, When two objects of like charge are near one another, the lines of force repel each other, as shown in the figure below.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is potential differance?

A

Potential difference is the term used to describe the size of the electrostatic force between two charged objects. If there are two objects with a potential difference, with a charged body between them, the charged body will try to move in one direction, depending upon the polarity of the charged body. The figure below shows the electrostatic force lines between three such charged objects.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is Electromotive force?

A

Electromotive force (EMF) is the sum of the potential differences of all charged particles in the electrostatic field. Due to the force of the electrostatic field, the electrical charges have the ability to do work by moving another charged particle by attraction and/or repulsion. Potential refers to this ability to do work; therefore, if one charge is different from another, there is a potential difference between them.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the basic unit of measure of potential difference?

A

The basic unit of measure of potential difference is the volt. The symbol for potential difference is V, indicating the ability to do the work of forcing electrons to move.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The strength of the attraction or of the repulsion force between two charged objects depends upon what two factors?

A
  1. The amount of charge on each object.
  2. The distance between the objects.

This is called Coulomb’s Law

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The force that holds electrons in their orbits is called:

A. Electrostatic force

B. Coulomb force

C. Electromotive force

D. Voltage

A

A. Electrostatic force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Select all that are correct:

According to Coulomb’s Law, the force between two charged objects…

A. decreases as distance between the objects increases.

B. increases as the distance between the objects increases.

C. increases as the magnitude of either charge increase.

D. is independent of the magnitude of charge on the objects.

A

A. decreases as distance between the objects increases.

C. increases as the magnitude of either charge increase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Match the following terms to their appropriate definitions.

A.Materials with electrons that are loosely bound to their atoms, or materials that permit free motion of a large number of electrons

B.Materials with electrons that are tightly bound to their atoms and require large amounts of energy to free them from the influence of the nucleus

C.Materials that conduct electricity, but offer opposition to current flow

D.Flow of positive charges (holes) through a conductor

  1. Conductor
  2. Insulator
  3. Resistor
  4. Conventional current
A
  1. A
  2. B
  3. C
  4. D
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Match the parameters with the correct units of measurement.

A.Henry

B.Farad

C.Siemen

D.Hertz

  1. Frequency
  2. Inductance
  3. Capacitance
  4. Conductance
A
  1. D
  2. A
  3. B
  4. C
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is OHM’s Law

A

E or V= I x R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How much current would a new hot tub draw if it will run at 220 volts and the resistance is 8 ohms?

A.0.275 A

B.3.63 A

C.27.5 A

D.36.6 A

A

C.27.5 A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Select all that are true. According to the Law of Magnetism, . . .

A.unlike magnetic poles attract.

B.like magnetic poles repel.

C.magnets can be made of any kind of material.

D. magnetism is caused by metal forging and does not occur naturally

A

A.unlike magnetic poles attract.

B.like magnetic poles repel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Match the following terms to their appropriate definitions.

A.Opposition to the production of flux in a material

B.The ability of a material to concentrate magnetic lines of flux

C.The group of magnetic field lines emitted outward from the north pole of a magnet

D.The strength of a magnetic field in a coil of wire

  1. Reluctance
  2. Magnetic flux
  3. Permeability
  4. Magnetomotive force
A
  1. A
  2. C
  3. B
  4. D
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Match the following terms to their appropriate definitions.

A.Iron, steel, nickel, cobalt, alnico and peralloy

B.Aluminum, platinum, manganese, and chromium

C.Bismuth, antimony, copper, zinc, mercury, gold, and silver

  1. Diamagnetic material
  2. Ferromagnetic material
  3. Paramagnetic material
A
  1. C
  2. A
  3. B
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How do you use the Left handed rule for Current-Carrying Conductors

A

•The illustration below helps explain the use of the left-hand rule:

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The left-hand rule for current-carrying conductors will work for both electron flow and conventional flow problems.

A.True

B.False

A

B.False

•Remember that the Left-Hand Rule for current-carrying conductors works with electron flow. If using conventional current, a right-hand rule would be used to depict the magnetic lines of force.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How do you use the Left handed rule for Coils?

A

•This figure illustrates the left-hand rule for coils:

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

A student is properly demonstrating the left-hand rule for coils to another student. If his fingers wrap around the coil in the direction of current flow, his thumb will be pointing. . .

A.vertically down from the coil.

B.toward the south magnetic pole.

C.vertically up from the coil.

D.toward the north magnetic pole.

A

D.toward the north magnetic pole.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

The expenditure of energy to realign magnetic domains in a ferromagnetic material is called. . .

A.polarity reversal.

B.hysteresis.

C.hysteresis loss.

D.magnetic permeability.

A

C.hysteresis loss.

28
Q

According to Faraday’s Law, which of the following factors influence the magnitude of induced voltage? (Select all that are correct.)

A.Diameter of the conductor

B.Length of the conductor

C.How fast the conductor crosses line of flux

D.Number of turns in the coil

A

C.How fast the conductor crosses line of flux

D.Number of turns in the coil

29
Q

Match the electrical symbols with their components.

A.Fuse

B.Battery

C.Diode

D.Capacitor

E.AC power source

F.Relay

A

From top to bottom.

  1. F. Relay
  2. D. Capacitor
  3. B. Battery
  4. C. Diode
  5. E. AC power source
  6. A. Fuse
30
Q

Match the following terms to the appropriate definitions.

A.Show wiring connections to trace the operation of the circuit from beginning to ending in an easy-to-follow manner, standard way to show information about electrical circuits.

B.Shows highly complex systems without showing the actual physical connections between components and individual conductors.

C.Shows the relationship between component groups, or stages in a circuit.

D.Shows wiring connections in an easy-to-follow manner.

  1. One-line diagram
  2. Wiring diagram
  3. Schematic diagram
  4. Block diagram
A
  1. B
  2. D
  3. A
  4. C
31
Q

Match the following terms to the appropriate definitions.

A.Circuit with a break in the circuit preventing a complete path so that no current flows.

B.Circuit that offers very little resistance to current flow and can cause dangerously high current flow through the circuit.

C.Circuit that has two or more components connected across the same voltage source.

D.Circuit where there is only one path for current flow.

  1. Series Circuit
  2. Parallel Circuit
  3. Open Circuit
  4. Short Circuit
A
  1. D
  2. C
  3. A
  4. B
32
Q

A device which senses abnormal conditions and closes contacts is called a:

A.breaker

B.safety sensor

C.relay

D.thermal fuse

A

C.relay

33
Q

Match the following terms to the appropriate definitions.

A.Cells that cannot be returned to a good condition, or recharged after their voltage output has dropped to a value that is not usable.

B.A solution which is capable of conducting an electric current.

C.A current of one ampere flowing for one hour.

D.The length of time that a storage battery will operate at a certain discharge rate; usually given in ampere-hours.

  1. Capacity
  2. Primary cell
  3. Ampere-Hour
  4. Electrolyte
A
  1. D
  2. A
  3. C
  4. B
34
Q

Components of a simple voltaic cell include _____________. (Select all that are correct.)

A.electrolyte solution

B.terminals

C.hydrochloric acid

D.two electrodes

A

A.electrolyte solution

D.two electrodes

35
Q

The electrolyte in a lead-acid battery is_____________________.

A.made of sulfuric acid and mineral oil

B.chosen for its properties as a non conductor

C.a solution of sulfuric acid and pure water

D.not involved in the chemical process, but just works as an insulating medium between the electrodes

A

C.a solution of sulfuric acid and pure water

36
Q

A series connected battery provides a higher voltage than connecting the same cells in parallel.

A.True

B.False

A

A.True

  • Cells connected in series increase the total voltage output of the battery
  • Cells connected in parallel give battery greater current capacity
37
Q

Match the following terms to the appropriate definitions.

A.Electrolyte is a paste

B.Rechargeable dry cell

C.Longer life than carbon zinc cell

D.Electrolyte is a liquid solution

  1. Wet cell
  2. Dry cell
  3. Nickel-cadmium cell
  4. Alkaline cell
A
  1. D
  2. A
  3. B
  4. C
38
Q

Battery temperatures exceeding 105°F can cause damage and early failure of the battery.

A.True

B.False

A

B.False

125°F and higher damages the battery and cause early failure

39
Q

Series Circuit Demonstration

A series circuit has a 50Ω, a 75Ω, and a 100Ω resistor in series as shown below. Find the voltage necessary to produce a current of 0.5 amps

A

112.5V

40
Q

Compound Circuit Demonstration

•Given the following:

–The voltage source is 12 V.

A = 6 ohms
B = 24 ohms
C = 12 ohms

•Find the current flow through each resistor and the equivalent resistance for resistors B and C.

A

The current flow through each risistor is.

A 0.86A

B 0.29A

C 057A

The equivalent resistance for resistors B and C is 8Ω

41
Q

A 120 V battery is connected in series with three resistors: 40Ω, 60Ω, and 100Ω. Find the voltage across each resistor.

A.V1 = 24 volts, V2 = 36 volts, V3 = 60 volts

B.V1 = 40 volts, V2 = 60 volts, V3 = 100 volts

C.V1 = 30 volts, V2 = 30 volts, V3 = 60 volts

D.V1 = 20 volts, V2 = 40 volts, V3 = 60 volts

A

A.V1 = 24 volts, V2 = 36 volts, V3 = 60 volts

42
Q

Given the voltage source is 24 VDC,

RA = 12 ohms
RB = 12 ohms
RC = 6 ohms

what is the voltage drop across RC?

A.8.0 volts

B.9.6 volts

C.24 volts

D.4.8 volts

A

D.4.8 volts

43
Q

The negative poles in the circuit shown are found at ____________.

A.the left of resistor A and the left of resistor C

B.the right end of resistor A and the left end of resistor C

C.the bottom end of resistor B and the right end of resistor A

D.the left end of resistor A and the right end of resistor C

A

D.the left end of resistor A and the right end of resistor C

44
Q

Kirchhoff’s Voltage Law states that the sum of voltage entering a junction must equal the sum of voltage exiting that junction.

A.True

B.False

A

B.False

Kirchhoff’s First Law (Voltage)

  • Describes voltage in closed loop (circuit)
  • States that the sum of the voltage drops around a closed loop (circuit) is equal to the sum of the voltage sources of that loop (circuit)
  • Another way of stating this law is that the algebraic sum of the voltage sources and voltage drops in a closed loop (circuit) must always be equal to zero
45
Q

Kirchhoff’s Voltage Law Demonstration

What is the current flow in the figure below? Assume that the current is flowing in the direction shown.

A

I = -0.5A

46
Q

Kirchhoff’s Law Demonstration

•Find I2 in the circuit below using Kirchhoff’s voltage and current laws.

A

1Amp

47
Q

Given the following:

A = 20 V
B = 12 V
C = 15 ohms
D = 12 ohms

Find the current in this loop.

A.10.7 amps

B.1.2 amps

C.2.7 amps

D.0.3 amps

A

B.1.2 amps

48
Q

Given the following:

A = 24 V
B = 12 V
C = 6 ohms
D = 12 ohms
E = 6 ohms

Find the current through each resistor.

A.IC = - 3.6amps, ID = - 1.2 amps, IE = - 2.4 amps

B.IC = -1.2 amps, ID = -0.4 amps, IE = -0.8 amps

C.IC = 1.2 amps, ID = 0.4 amps, IE = 0.8 amps

D.IC = 3.6 amps, ID = 1.2 amps, IE = 2.4 amps

A

C.IC = 1.2 amps, ID = 0.4 amps, IE = 0.8 amps

49
Q

The left-hand rule for current-carrying conductors states that _____________.

A.when the thumb points in the direction of electron flow, it is also pointing in the direction of the induced North magnetic pole

B.when the thumb points in the direction of electron flow, the fingers will wrap around the conductor in the direction of the magnetic lines of force (South to North)

C.when the thumb points in the direction of conventional current flow, the fingers will wrap around the conductor in the direction of the magnetic lines of force (North to South)

D.when the thumb points in the direction of electron flow, the fingers will wrap around the conductor in the direction of the magnetic lines of force (North to South)

A

C.when the thumb points in the direction of electron flow, the fingers will wrap around the conductor in the direction of the magnetic lines of force (North to South)

50
Q

The right-hand rule for motors states that _______________________.

A.when the middle finger is pointed in the direction of the magnetic field lines, and the forefinger is pointed in the direction of current flow, the thumb will point in the direction of force (motion)

B.when the middle finger is pointed in the direction of the magnetic field lines, and the thumb is pointed in the direction of current flow, the forefinger will point in the direction of force (motion)

C.when the forefinger is pointed in the direction of the magnetic field lines, and the thumb is pointed in the direction of current flow, the middle finger will point in the direction of force (motion)

D.when the forefinger is pointed in the direction of the magnetic field lines, and the middle finger is pointed in the direction of current flow, the thumb will point in the direction of force (motion)

A

D.when the forefinger is pointed in the direction of the magnetic field lines, and the middle finger is pointed in the direction of current flow, the thumb will point in the direction of force (motion)

51
Q

Select all of the statements about DC motors that are correct.

A.The physical dimensions of the motor do not influence torque.

B.The magnitude of armature current does not influence torque.

C.Torque is the product of the force exerted on the rotor and the radius of the rotor.

D.The field strength, in part, determines force.

A

C.Torque is the product of the force exerted on the rotor and the radius of the rotor.

D.The field strength, in part, determines force.

52
Q

Select all of the statements that are true about CEMF.

A.Counter-electromotive force always opposes the applied force.

B.Hysteresis causes counter-electromotive force

C.Rotation of the current-carrying conductor in the magnetic field causes counter-electromotive force.

D. Counter-electromotive force exists when the rotor is stationary

A

A.Counter-electromotive force always opposes the applied force.

C.Rotation of the current-carrying conductor in the magnetic field causes counter-electromotive force.

53
Q

Increasing field resistance will increase DC motor speed.

A.True

B.False

A

A.True

  • An increase in field current will cause field flux (ΦF) to increase
  • Conversely, if the resistance of the field is increased, field current and field flux will decrease
  • If the field flux of a DC motor is decreased, the motor speed will increase
54
Q

Starting resistors are needed in DC motors to . . ? (Select all that are correct.)

A.overcome the starting resistance.

B.limit the voltage during a motor start.

C.compensate for the high values of CEMF at startup.

D.limit the current during a motor start.

A

D.limit the current during a motor start.

55
Q

The common ratings for DC motors include _________________________. (Select all that are correct.)

A.speed

B.ambient temperature

C.starting current

D.continuous power

A

A.speed

D.continuous power

•Nameplate ratings of DC motor typically refer to conditions of voltage, current, speed, and power within which motor is normally operated

56
Q

Match the following terms to the correct descriptions.

A .Applying pressure to certain crystals (such as quartz or Rochelle salts) or certain ceramics (like barium titanate) forces electrons out of orbit in the direction of the force.

B. Photons in a light beam strike the surface of a material and release their energy to the atomic electrons of the material. This energy transfer may dislodge electrons from their orbits around the surface of the substance.

C. A chemical reaction produces and maintains opposite charges on two dissimilar metals that serve as the positive and negative terminals.

D. Producing a voltage by rotating coils of wire through a stationary magnetic field, or by rotating a magnetic field through stationary coils of wire

  1. Electrochemistry
  2. Piezoelectric effect
  3. Magnetic induction
  4. Photoelectric effect
A
  1. C
  2. A
  3. D
  4. B
57
Q

Select all statements that are true.

A. A half-wave rectifier can be built with one diode.

B. Rectifiers convert DC power into AC power.

C. A full-wave rectifier can be built with one diode.

D. A forward-biased diode allows current flow with little resistance

A

A. A half-wave rectifier can be built with one diode.

D. A forward-biased diode allows current flow with little resistance

58
Q

Commutation is:

A.a means of increasing the voltage output of a DC generator.

B.a means of increasing the total power output of a DC generator.

C.the positioning of the DC generator brushes so that the commutator segments change brushes at the same time the armature current changes direction to convert from AC to DC at the brushes of a DC machine.

D.the positioning of the DC generator brushes so that the commutator segments change brushes at the same time the armature current changes direction to convert from DC to AC at the brushes of a DC machine.

A

C.the positioning of the DC generator brushes so that the commutator segments change brushes at the same time the armature current changes direction to convert from AC to DC at the brushes of a DC machine.

59
Q

List Three things required to induce a voltage.

A

–A magnetic field

–A conductor

–Relative motion between the conductor and the magnetic field

60
Q

Relative motion between the conductor and the magnetic field is necessary to induce voltage.

A.True

B.False

A

A.True

61
Q

Select all statements that are true.

A.The counter-electromotive force always opposes the applied voltage.

B.The counter-electromotive force always opposes current flow.

C.The counter-electromotive force is induced if the rotor is not turning.

D.The counter-electromotive force is induced only in rotating armature machines.

A

A.The counter-electromotive force always opposes the applied voltage.

B.The counter-electromotive force always opposes current flow.

62
Q

The left-hand rule for generators is used as follows: (select the best answer)

A.Point the index finger of your left hand in the direction of the magnetic field (from north to south) and point the thumb in the direction of motion of the conductor, the middle finger will point in the direction of electron flow.

B.Point the index finger of your left hand in the direction of the magnetic field (from north to south) and point the thumb in the direction of motion of the conductor, the middle finger will point in the direction of conventional current flow.

C.Point the thumb of your left hand in the direction of the magnetic field (from north to south) and point the index finger in the direction of motion of the conductor, the middle finger will point in the direction of electron flow.

D.Point the thumb of your left hand in the direction of the magnetic field (from north to south) and point the index finger in the direction of motion of the conductor, the middle finger will point in the direction of conventional current flow.

A

A.Point the index finger of your left hand in the direction of the magnetic field (from north to south) and point the thumb in the direction of motion of the conductor, the middle finger will point in the direction of electron flow.

63
Q

Which of the following does not affect the magnitude of voltage generated?

A.Speed of rotation of the armature

B.Direction of rotation of the armature

C.Number of current loops in the armature

D.Magnetic field strength

A

B.Direction of rotation of the armature

64
Q

Match each DC Generator Rating with the limiting factor it is based on.

A.Insulation type and design

B.Size of conductors in the armature

C.Mechanical limits of the prime mover

D.Mechanical construction of the rotor

  1. Speed
  2. Power
  3. Current
  4. Voltage
A
  1. D.
  2. C.
  3. B.
  4. A.
65
Q
A

Foundation (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions