ELECTRICAL FINAL

Most conductors tend to Select one: a. oscillate when voltage is applied b. decrease in resistance with increase in temperature c. shrink when heated d. melt when voltage is applied e. increase in resistance with increase in temperature

e

Ohms Law can be stated as Select one: a. R = I/E b. volts equals ohms divided by amperes c. watts times ohms equal volts d. I = R/E e. E = IR

e

Since the discovery of electrons, it has been determined that electrons are a negative charge and flow from Select one: a. positive to negative b. a lower potential to a higher potential c. the battery to the source d. north to south e. negative to positive

e

The battery of an electrical circuit Select one: a. decreases the resistance b. maintains lighting for the circuit c. withholds neutrons from the circuit d. gives a load to the circuit e. supplies electromotive force

e

The black demand pointer of a power meter Select one: a. moves the red pointer b. always reads the current demand c. resets automatically d. indicates the amperage being drawn e. must be manually reset

e

The electromagnetic field for a DC machine is termed the Select one: a. commutator b. armature c. brush gear d. yoke Incorrect e. field poles

e

The equivalent resistance of three resistances 7 ohms, 19 ohms and 41 ohms connected in parallel is Select one: a. 0.16 ohms b. 18.75 ohms c. 85 ohms d. 62.5 ohms e. 4.55 ohms

e

The opposition a device or material offers to the flow of electric current, is known as: Select one: a. a voltage drop b. an insulator c. counterflow d. a short circuit e. a resistance

e

The three main types of DC generators are the: 1. compound wound 2. parallel wound 3. series wound 4. reverse wound 5. shunt wound Select one: a. 2, 4, 5 b. 1, 2, 4 c. 2, 3, 5 d. 3, 4, 5 e. 1, 3, 5

e

The value of the current flow in an electric circuit, where the voltage is 28 volts and the resistance is 2.5 ohms is Select one: a. 36 amperes b. 0.25 amperes c. 4 watts d. 3.6 amperes e. 11.2 amperes

e

Under normal circumstances, the heat produced by the electrical wires of a circuit are very small due to the Select one: a. insulation wrapped around b. large diameter of the conductor c. small diameter of the conductor d. long length of the conductor e. low resistance of the conductor

e

Utility companies have a surcharge to their customers based on Select one: a. the maximum voltage used b. the maximum amperage used c. system capacitance d. transformer efficiency e. peak demand

e

An electric motor is designed for a current of 23 amperes with an applied voltage of 240 volts. calculate the efficiency of the motor in percentage if the rated output is 4.85 kW Answer 1 calculate the power consumed in watts

88, 5520

The unit of current flow is the Select one: a. watt b. ampere c. hertz d. ohm e. volt

B

A closed electrical circuit will Select one: a. allow current to flow b. be series only c. not allow current to flow d. be parallel only e. contain an open switch or relay contact

a

A conductor supplied with current while in a magnetic field will Select one: a. tend to move at right angles to the flux lines b. tend to remain stationary c. form a solenoid d. have a current induced into it e. want to move with the flux lines

a

Atoms that have greater numbers of electrons in the outer shell are Select one: a. not good conductors b. good conductors c. neutrally charged d. not good insulators e. positively charged

a

Clamp-on ammeter readings may be inaccurate if Select one: a. jaws are dirty or misaligned b. circuit voltage is too high c. circuit resistance is too low d. circuit power is too high e. conductor insulation is too thick

a

Current flow is Select one: a. proportional to the applied voltage b. increased by a decrease in applied voltage c. reversed by a resistance d. proportional to the resistance e. inversely proportional to the applied voltage

a

Electromotive force Select one: a. is capable of moving a quantity of electrons at some rate per period of time b. induces resistance to an open circuit c. is increased by a resistor d. is increased by a voltage drop e. is able to move ohms through a resistance

a

If an electrical ___________________ is placed across a conductor, the electrons will drift from the negative end towards the positive end of the conductor, assuming the electron theory. Select one: a. potential b. wire c. resistance d. meter e. current

a

In an equivalent circuit developed from a multi-resistor series circuit Select one: a. the sum of voltage drops across the original resistances will be equal to the voltage drop of the equivalent circuit b. voltage drop will be the same as for each of the original resistances c. the resistance will be the reciprocal sum of the original resistances d. amperage flowing will be different than the original circuit amperage flowing through each resistance e. original circuit resistances will each have to be the same as the equivalent resistance

a

Iron and steel may be magnetized by rubbing the metal with Select one: a. a magnet b. a brass rod c. stainless steel d. an iron filing compound e. steel wool

a

The direction of the ______________ due to motor action may be determined using the Left Hand Rule. Select one: a. force b. applied voltage c. rotation d. resistance e. current

a

The maximum voltage generated by a single loop DC generator occurs when the conductor is cutting the magnetic lines of force at an angle of Select one: a. 90 degrees b. 120 degrees c. zero degrees d. 45 degrees e. 180 degrees

a

The property of resistance to conducting magnetic lines of force is known as Select one: a. reluctance b. repulsion c. voltage drop d. impedance e. resistance

a

The total number of lines of force per square metre in a magnetic field is Select one: a. called the magnetic flux b. controlled by varying the temperature c. determined by the north magnetic pole d. depends on the force of gravity e. known as the EMF

a

The total resistance of three resistances in a series circuit can be given as Select one: a. R1 + R2 + R3 b. 1/ R1 + 1/ R2 + R3 c. R1 x R2 x R3 d. (R1 x R2 x R3)/3 e. R1/1 + R2/2 + R3/3

a

The voltage produced in each phase of a three phase generator is displaced by __________ electrical degrees from the other phases. Select one: a. 120 b. 0 c. 30 d. 90 e. 60

a

The voltage required to force a current of 12 amps through a resistance of 3.5 ohms would be Select one: a. 42 volts b. 7.5 volts c. 33 volts d. 0.33 volts e. 3 volts

a

When a conductor is moved to cut magnetic flux lines at an angle of 90 degrees Select one: a. voltage generated will be maximum b. current will flow with the least resistance c. maximum resistance to current flow is attained d. motion will be easiest e. motor action will be experienced

a

When one ampere of current flows through a resistance by the application of one volt the resistance will be Select one: a. one ohm b. one watt c. one kilovolt ampere d. one kilowatt e. one ampere

a

When using an electrical meter to check that a circuit is safe to work on, it is important to verify the proper scale, current, or both that is being used because Select one: a. it may appear that no voltage or current is present and therefore safe b. the meter will be damaged c. the user will be subjecting himself or herself to danger d. the main high voltage transformer circuit will be opened e. electrical wiring will be damaged by fire or overheating

a

_______________________ is an electromotive force. Select one: a. The volt b. Amperage c. The watt d. The ohm e. Power

a

A basic law of electricity is, unlike charges attract each other and like charges Select one: a. are neutralized b. repel each other c. reduce power output d. attract each other e. hold each other

b

A material that conducts electrical current is called Select one: a. an electromotive force b. a conductor c. a circuit d. a conduit e. a volt

b

An open circuit is one in which Select one: a. a switch is closed b. a switch is open c. the current flows through the resistance d. voltage may exit e. the wires are bare

b

Current flow direction and intensity will Select one: a. affect the voltage b. affect magnetic field direction and intensity c. not affect electromagnetic field direction d. not affect electromagnetic field intensity e. affect the resistance of a circuit

b

Faraday discovered Select one: a. the Right Hand Rule for generators b. that a conductor will have a voltage induced if it cuts magnetic flux c. the Right Hand Rule for conductors d. that current flows from positive to negative e. the Left Hand Rule for motors

b

If a conductor is held stationary and a magnetic field is moved across it, it forms what is known as Select one: a. transformer action b. generator action c. electromagnetism d. motor action e. conduction

b

If two unlike poles are placed adjacent to each other there is Select one: a. a force of repulsion between the magnets b. a force of attraction between the magnets c. a production of AC power d. a development of iron filings between the magnets e. a reversal of the north and south poles of each magnet

b

In an atom the electrons Select one: a. orbit around each other b. are attracted to the protons c. are large in size when compared to the protons d. are repelled by the neutrons e. orbit only the neutrons

b

Neglecting the efficiency, a 11 kW motor connected to a 240 volts supply, the amperage will be Select one: a. 3.75 amperes b. 45.83 amperes c. 26.667 amperes d. 2.667 amperes e. .0375 amperes

b

The connection provided on DC motors to supply the armature with power Select one: a. are field poles b. is a commutator c. are slip rings d. is a rheostat e. is a rotating conductor

b

The field strength of an alternator may be changed by varying the amplitude of the DC power, supplied to the rotating field by: 1. the use of a field rheostat 2. a reducing gear 3. changes of the input frequency 4. electronic control Select one: a. 1, 2, 3 b. 1, 4 c. 3, 4 d. 2, 3, 4 e. 1, 3, 4

b

The voltage required to be supplied to a 9 kW motor drawing 19 amperes is Select one: a. 2 kilovolts b. 473.7 volts c. 288.3 volts d. 5 kilovolts e. 50 kilovolts

b

When using Fleming's Left Hand Rule, the index finger represents Select one: a. motor action motion direction b. motor action flux direction c. generator conductor motion direction d. generator action flux direction e. motor action direction of current flow

b

A clamp-on ammeter measures current flow by using Select one: a. differential voltage b. differential current flow between two conductors c. a basic transformer principle d. a portion of circuit resistance e. electromagnetism

c

A current carrying conductor being moved by a magnetic field is the principle known as Select one: a. generator action b. hydro-electrics c. motor action d. electrolysis e. magnetic flux

c

A kilowatt hour meter has a small motor which Select one: a. turns at a constant speed b. slows down as power consumption increases c. has a speed proportional to power consumption d. moves the meter demand pointer e. indicates the multiplier to be used when reading the meter

c

A power meter Select one: a. reads the actual power consumed b. does not require a multiplying factor c. reads only a small percentage of the actual load d. will calculate the actual cost of the power e. does not take into account the system voltage

c

A property of a magnet is that it will always point in the north and south direction, when Select one: a. submerged in oil b. it is demagnetized c. freely suspended in the air d. in the presence of iron filings e. charged with electricity

c

Ammeters are connected with the negative or black lead connected to the Select one: a. positive side of the circuit b. north pole of the circuit c. negative side of the circuit d. switch of the circuit e. neutral wire of the circuit

c

An ampere is the _______________ of current flow. Select one: a. cause b. cause of increase c. measurement d. resistance e. cause of reduction

c

Electrical power can be determined by the formula Select one: a. E = IR b. I = ER c. P = IE d. R = EI e. P = IR

c

Electrons are negatively charged particles Select one: a. which seek open circuits b. which can easily flow through insulators c. orbiting about the nucleus of an atom d. firmly attached to the neutrons of an atom e. flowing through the atoms centre

c

Equivalent resistance is decreased Select one: a. when voltage is decreased b. if the amperage is increased c. when a circuit is in parallel d. when a circuit is opened e. when a circuit is in series

c

If the applied voltage in a circuit is 220 volts and the current flow is 2.3 amperes the resistance of this circuit is Select one: a. 25 Watts b. 40 Watts c. 95.6 Ohms d. .025 Ohms e. 360 Ohms

c

Magnetic flux can be said to be Select one: a. lines of force flowing in a magnet b. a zone of lines outside a magnet Incorrect c. lines of force outside a magnet and flowing "N" to "S" d. lines of force within a magnet and flowing "N" to "S" e. lines of force flowing "S" to "N" outside a magnet

c

The basic unit of mechanical or electric power is the Select one: a. Newton b. ampere c. watt d. ohm e. volt

c

The electrical pressure that causes current flow through a circuit is Select one: a. amperage b. the watt c. electromotive force d. the ohm e. very high voltage

c

The flow of electrons in a uniform direction from atom to atom through a circuit, is known as Select one: a. voltage drop b. potential difference c. current d. a short circuit e. electromotive force

c

The flow of electrons in a uniform direction is called Select one: a. potential difference b. direct current c. electrical current flow d. voltage drop e. electromotive force

c

The force required to produce a current of one ampere through a resistance of one ohm, is Select one: a. one watt b. one kilovolt c. one volt d. one ampohm e. one megawatt

c

The load current has no effect on the field excitation of a Select one: a. reverse wound exciter b. shunt wound generator c. separately excited generator d. compound wound generator e. series wound generator

c

The minimum voltage generated by a single loop DC generator occurs when the conductor is cutting the magnetic lines of forces at an angle of Select one: a. 270 degrees b. 120 degrees c. 180 degrees d. 90 degrees e. 45 degrees

c

The space or zone around a magnet through which lines of force travel is termed Select one: a. magnetic strength b. permeability c. magnetic field d. magnetic flux e. reluctance

c

The voltage drop across a 16 ohm resistor with 4.5 amps flowing would be Select one: a. 150 b. 0.5 c. 72 d. 2 e. 20

c

The watt is an electrical unit of measure for Select one: a. current flow b. potential difference c. power d. magnetic flux strength e. resistance

c

Three factors which control the electromotive force developed by a DC generator are the: 1. size of the frame 2. speed with which conductors cut the magnetic lines of force 3. number of conductors cutting the magnetic lines of force 4. diameter of the conductors 5. strength of the magnetic flux 6. diameter of the armature Select one: a. 2, 5, 6 b. 1, 4, 6 c. 2, 3, 5 d. 3, 4, 6 e. 1, 3, 6

c

When a material or substance does not form a magnetic flux easily it is said to have Select one: a. low field reactance b. resistance c. reluctance d. permeability e. low magnetic flux

c

When a number of electrons pass a given point over a specific time period the energy may be referred to as Select one: a. voltage b. power or watts c. an ampere d. electromotive force e. an ohm

c

When magnetic flux lines travel and meet in opposing directions the result can be Select one: a. electromagnetism b. solenoid action c. motor action d. reluctance e. generator action

c

_____________ current flow is from positive to negative. Select one: a. Reversed b. Electron c. Conventional d. Generated e. Static

c

A triple pole single throw switch is one Select one: a. which requires three toggles b. that has three magnetic poles c. which cannot be operated manually d. which opens and closes three wires of an electric circuit e. which is used for three phase circuits only

d

A voltmeter is connected to a circuit Select one: a. in series b. in series and parallel c. in series and shunt d. in parallel e. between the last resistance and the source

d

An electrical device which is designed to start and stop current flow is the Select one: a. fuse b. potentiometer c. circuit breaker d. switch e. resistor

d

An insulator is material that will not _________________ an electrical current. Select one: a. retard b. slow c. reduce d. conduct e. resist

d

Batteries Select one: a. do not pose any immediate electrical hazards b. produce a steady AC voltage c. produce a varying DC voltage d. produce a steady DC voltage e. produce a varying AC voltage

d

The basic unit of electrical power is the watt, which is the result of Select one: a. ohms plus amperes b. ohms times amperes c. volts times ohms d. volts times amperes e. volts plus amperes

d

The field strength of an alternator can be adjusted by varying the amplitude of the DC power supplied to the Select one: a. rotating stator b. alternator frame c. stator windings d. rotating field e. shaft

d

The most common measurement made with a meter is Select one: a. amperage b. watts c. resistance d. voltage e. capacitance

d

The property which determines whether or not a material will be easily magnetized or not is called Select one: a. conductivity b. reaction c. fluctuation d. permeability e. magnetism

d

The purpose of having an upward movement of a switch handle to close the switch is Select one: a. because it is easier to operate when opening the switch b. to meet the requirements of the electrical act c. it indicates the condition of the circuit d. to prevent the switch from closing due to gravity e. to have the handle out of the way

d

The right hand rule is used to Select one: a. determine the direction of motor rotation b. determine magnetic flux rotation c. determine the frequency of an alternator d. determine the direction of induced current flow e. indicate the speed of a rotor

d

The unit for opposition to current flow is the Select one: a. watt b. newton c. ampere d. ohm e. volt

d

The unit of measure for electrical current flow is the Select one: a. Watt b. Ohm c. Volt d. Ampere e. Electron

d

Three resistances of 15, 34, and 62 ohms make up a series circuit. Supply voltage is 240. The current flowing would be Select one: a. 20.38 amps b. 60 amps c. 8.42 amps d. 2.16 amps e. 5.18 amps

d

Three resistors of 15, 40, and 100 ohms are connected in parallel and the circuit amperage is 35. The applied voltage would be Select one: a. 3.33 b. 7,200 c. 12,000 d. 344.3 e. 0.33

d

Voltage is Select one: a. the rate of Ohm flow b. the rate of current flow c. the rate of electron flow d. electromotive force e. required for current resistance

d

What power is dissipated by a resistor with a supply voltage of 240 volts and current of 5.3 amperes? Select one: a. 15 watts b. 960 ohms c. 96 kilowatts d. 1272 watts e. 15 ohms

d

When current flows in a conductor Select one: a. no heat can be generated b. all magnetic forces are dissipated c. A.C. voltage is generated d. a circular magnetic field is set up around the conductor e. the voltage is reduced in the conductor

d

When like poles of a magnet are placed adjacent to each other they will Select one: a. have no reaction b. bend c. increase in temperature d. repel each other e. be attracted to each other

d

When reading the dials of a power meter, read Select one: a. them in the sequence shown by the letters under each b. them from left to right c. the ones which rotate clockwise first d. them from right to left e. them only at the request of the utility company

d

A conductor's resistance is Select one: a. directly proportional to its diameter b. measured in micro-Newtons c. directly proportional to its cross-sectional area d. not affected by the cross-sectional area e. inversely proportional to its cross-sectional area

e

An advantage of having an alternator with a rotating field is, that the size of the rotating mass is Select one: a. increased b. removed c. constant d. easily heated e. reduced

e

Current flow is inversely proportional to the Select one: a. wattage b. voltage c. amperage d. conductance e. resistance

e

If the power dissipated by a resistor is 1.2 kW when supplied with 110 volts, the amperage will be Select one: a. 19.006 amperes b. 91.666 amperes c. 1320 amperes d. 132 amperes e. 10.909 amperes

e

Magnetic field direction and intensity depend on the Select one: a. copper content of the magnet b. temperature of the EMF c. specific heat of the conductor d. EMF of the magnet e. direction and intensity of current flow

e