REM A LVL 1, 2, & 3

Question 1

When one of three series resistors is removed from a circuit and the circuit is reconnected, the current

A. increases by one-third
B. decreases by one-third
C. increases
D. decreases by the amount of current through the removed resistor

Answer 1

C. increases

Question 2

Carbon-composition resistors:

A. Can handle lots of power.
B. Have capacitance or inductance along with resistance.
C. Work better for ac than for dc.
D. Are comparatively nonreactive.

Answer 2

D. Are comparatively nonreactive.

Question 3

Good engineering practice usually requires that a series-parallel resistive network be made:

A. From resistors that are all the same
B. From a series combination of resistors in parallel
C. From resistors that are all very rugged
D. From a parallel combination of resistors in series

Answer 3

A. From resistors that are all the same

Question 4

Two resistors are in parallel. Resistor A carries twice the current of resistor B, which means that:

A. the voltage across A is twice that across B
B. the voltage across B is twice that across A
C. A has half the resistance of B
D. B has half the resistance of A

Answer 4

C. A has half the resistance of B

Question 5

A voltage across a series resistor circuit is proportional to?

A. The amount of time the circuit was on for
B. The power in the circuit
C. The value of the other resistances in the circuit
D. The value of the resistance itself

Answer 5

D. The value of the resistance itself

Question 6

Red, red, red, gold indicates
A. 2.2 K ohms
B. 220 ohms
C. 22 ohms
D. 22 K ohms

Answer 6

A. 2.2 K ohms

Question 7

In a mesh, the algebraic sum of all voltages and voltage drops is equal to zero.

A. Norton’s law
B. Kirchhoff’s first law
C. Superposition theorem
D. Kirchhoff’s second law

Answer 7

D. Kirchhoff’s second law

Question 8

Mesh analysis is best used together with what circuit law?

A. VDT
B. CDT
C. KVL
D. KCL

Answer 8

C. KVL

Question 9

The current flowing in the branches of a d.c. circuit may be determined using:

A. Kirchhoff’s laws
B. Faraday’s laws
C. Lenz’s law
D. Fleming’s left-hand rule

Answer 9

A. Kirchhoff’s laws

Question 10

When applying KVL, a closed path is commonly referred to as

A. node
B. branch point
C. loop
D. principal node

Answer 10

C. loop

Question 11

In a parallel circuit with a voltage source and several branch resistors, how is the total current related to the current in the branch resistors?

A. It decreases as more parallel resistors are
added to the circuit
B. It equals the average of the branch current
through each resistor
C. It is the sum of each resistors voltage drop
multiplied by the total number of resistors
D. It equals the sum of the branch current
through each resistor

Answer 11

D. It equals the sum of the branch current
through each resistor

Question 12

Which of the following is also known as
the dual of Thevenin’s theorem?

A. Maximum power transfer theorem
B. Norton’s theorem
C. Superposition theorem
D. Millman’s theorem

Answer 12

B. Norton’s theorem

Question 13

The primary method of analyzing a
circuit with two or more voltage sources
is usually

A. Kirchhoff’s law
B. Ohm’s law
C. Thevenin’s theorem
D. superposition

Answer 13

D. superposition

Question 14

Norton’s theorem gives

A. an equivalent current source in parallel
with an equivalent impedance
B. an equivalent current source in series with
an equivalent impedance
C. an equivalent voltage source in parallel
with an equivalent impedance

Answer 14

A. an equivalent current source in parallel
with an equivalent impedance

Question 15

A Thevenin equivalent circuit consists
of

A. a voltage source in series with a
resistance
B. two voltage sources and a resistance
C. a current source in parallel with a
resistance

Answer 15

A. a voltage source in series with a
resistance

Question 16

The primary method of analyzing a
circuit with two or more voltage sources
is usually

A. superposition
B. Thevenin’s theorem
C. Kirchhoff’s law

Answer 16

A. superposition

Question 17

Norton resistance is found by?

A. Shorting all voltage sources
B. Shorting all voltage sources and
opening all current sources
C. Opening all current sources
D. Opening all voltage sources and shorting
all current sources

Answer 17

B. Shorting all voltage sources and
opening all current sources

Question 18

The Norton current is the ___

A. Open circuit and short circuit current
B. Open circuit current
C. Short circuit current

Answer 18

C. Short circuit current

Question 19

Why would it be important to minimize
the mutual inductance between two
inductors?

A. To reduce unwanted coupling between
circuits
B. To reduce conducted emissions
C. To increase the energy transfer between
circuits

Answer 19

A. To reduce unwanted coupling between
circuits

Question 20

A series connected C -R circuit is
suddenly connected to a d.c. source of
V volts. Which of the statements is
false?

A. The initial voltage drop across the resistor
is IR, where I is the steady-state current
B. The capacitor voltage is equal to the
voltage drop across the resistor
C. The voltage drop across the resistor
decays exponentially
D. The initial capacitor voltage is zero

Answer 20

B. The capacitor voltage is equal to the
voltage drop across the resistor

Question 21

A material with a high dielectric
constant:

A. Acts to increase capacitance per unit
volume
B. Has no effect on capacitance
C. Causes a capacitor to become polarized

Answer 21

A. Acts to increase capacitance per unit
volume

Question 22

Inductors in series, assuming there is no
mutual inductance, combine:

A. Like resistors in series
B. In a way unlike any other type of
component
C. Like resistors in parallel

Answer 22

A. Like resistors in series

Question 23

The capacitance of a capacitor is the
ratio

A. Charge to potential difference between
plates
B. Potential difference between plates to
thickness of dielectric
C. Potential difference between plates to
plate spacing

Answer 23

A. Charge to potential difference between
plates

Question 24

The effect of inductance occurs in an
electrical circuit when:

A. none of these choices
B. the current is changing
C. the flux is changing
D. the resistance is changing

Answer 24

B. the current is changing

Question 25

If you have light bulbs marked 40 watts,60 watts and 100 watts, which one will use electrical energy the fastest? A. The 60 watt bulb B. The 40 watt bulb C. The 100 watt bulb

Answer 25

C. The 100 watt bulb

Question 26

In a series-connected string of holiday ornament bulbs, if one bulb gets shorted out, which of these is most likely? A. The current in the string will stay the same. B. All the other bulbs will go out. C. The current in the string will go up.

Answer 26

C. The current in the string will go up.

Question 27

If you measure all the voltage drops and the source voltage in a series circuit and add them together, taking into consideration the polarities, you will get a result equal to A. the source voltage B. the total of the source voltage and the voltage drops C. zero

Answer 27

C. zero

Question 28

Electrical current is measured in which of the following units? A. Ohms B. Amperes C. Volts

Answer 28

B. Amperes

Question 29

What must be known in order to calculate the energy used by an electrical appliance? A. current and time of operation B. power and time of operation C. current and resistance

Answer 29

B. power and time of operation

Question 30

How is the current in a DC circuit calculated when the voltage and resistance are known? A. Current equals voltage divided by resistance B. Current equals power divided by voltage C. Current equals resistance multiplied by voltage D. Current equals resistance divided by voltage

Answer 30

A. Current equals voltage divided by resistance

Question 31

What is the basic unit of electrical power? A. The ampere B. The watt C. The volt D. The ohm

Answer 31

B. The watt

Question 32

The effect of connecting an additional parallel load to an electrical supply source is to increase the A. resistance of the load B. p.d. across the load C. current taken from the source D. voltage of the source

Answer 32

C. current taken from the source

Question 33

What is the zero-voltage switch used for? A. To control low-voltage circuits B. To reduce radiation of high frequencies during turn-on of a high current to a load C. For extremely low-voltage applications D. To provide power to a circuit when power is lost

Answer 33

B. To reduce radiation of high frequencies during turn-on of a high current to a load

Question 34

Which of the following statements is false? A. Current is at a maximum at resonance in an a.c. circuit B. Apparent power÷True power gives power factor C. The product of r.m.s. current and voltage gives the apparent power in an a.c. circuit

Answer 34

B. Apparent power÷True power gives power factor

Question 35

A series connected C -R circuit is suddenly connected to a d.c. source of V volts. Which of the statements is false? A. The time constant of the circuit is given by CR B. The final value of the current is zero C. The current grows exponentially

Answer 35

C. The current grows exponentially

Question 36

Which of the following is a reason not to use wire-wound resistors in an RF circuit? A. The resistor's tolerance value would not be adequate for such a circuit B. The resistor's inductance could make circuit performance unpredictable C. The resistor could overheat D. The resistor's internal capacitance would detune the circuit

Answer 36

B. The resistor's inductance could make circuit performance unpredictable

Question 37

What device can be used to minimize the effect of RF pickup by audio wires connected to stereo speakers, intercom amplifiers, telephones, etc.? A. Diode B. Magnet C. Ferrite core

Answer 37

C. Ferrite core

Question 38

The most useful ac bridge for comparing capacitances of two air capacitors is _bridge. A. Schering B. De Sauty C. Wien parallel D. Wien series

Answer 38

B. De Sauty

Question 39

Hay's bridge is particularly useful for measuring. A. Self inductance B. Mutual inductance C. Inductive impedance with large phase angle

Answer 39

C. Inductive impedance with large phase angle

Question 40

As frequency increases. A. series RC impedance increases and parallel RC impedance decreases B. series RC impedance decreases and parallel RC impedance increases C. both series and parallel RC impedance decrease

Answer 40

C. both series and parallel RC impedance decrease

Question 41

When the frequency of an a.c. circuit containing resistance and inductance is increased, the phase angle of the circuit A. increases B. stays the same C. decreases

Answer 41

A. increases

Question 42

Each impedance R +jXL: A. All of these choices B. Corresponds to a unique point in the RL plane. C. Corresponds to a unique resistance. D. Corresponds to a unique inductive reactance.

Answer 42

A. All of these choices

Question 43

When the resistor voltage in a series RL circuit becomes less than the inductor voltage, the phase angle A. cannot be determined B. decreases C. is not affected D. increases

Answer 43

D. increases

Question 44

If the dielectric material between the plates of a capacitor is changed, all other things being equal: A. The value of Xc decreases negatively. B. The value of Xc does not change. C. You can't say what happens to XC without more data.

Answer 44

C. You can't say what happens to XC without more data.

Question 45

In the complex plane, the number 14- j5 is located in the A. first quadrant B. third quadrant C. fourth quadrant D. second quadrant

Answer 45

C. fourth quadrant

Question 46

In a Y-connected circuit, the magnitude of each line current is A. three times the corresponding phase current B. equal to the corresponding phase current C. zero

Answer 46

B. equal to the corresponding phase current

Question 47

What should be the impedance of a low pass filter as compared to the impedance of the transmission line into which it is inserted? A. Twice the transmission line impedance B. About the same C. Substantially higher

Answer 47

B. About the same

Question 48

If the resistance in parallel with a parallel resonant circuit is reduced, the bandwidth A. increases B. decreases C. becomes sharper

Answer 48

B. decreases

Question 49

Power factor is equal to: A. True power divided by apparent power B. Apparent power divided by true power C. Imaginary power divided by true power

Answer 49

A. True power divided by apparent power

Question 50

Parallel tuned circuits offer: A. low impedance at resonance B. very high impedance at resonance C. an impedance equal to resistance of the circuit

Answer 50

B. very high impedance at resonance

Question 51

When a series LCR circuit is tuned to the frequency of the source, the: A. line current leads the applied voltage B. impedance is maximum C. line current reaches maximum

Answer 51

C. line current reaches maximum

Question 52

How many types of power can be defined in an AC circuit? A. 3 B. 1 C. 5 D. 2

Answer 52

A. 3 In an AC circuit, we can define three types of power, namely, Instantaneous power, Average power, and Apparent power.

Question 53

What is the power factor in a pure resistive circuit? A. 0 B. Infinity C. 1 D. -1

Answer 53

C. 1 A circuit containing only a pure resistance in an AC circuit is known as a pure resistive AC Circuit. For a purely resistive circuit, the power factor is one,because the reactive power equals zero, i.e. Φ=0- Power factor (cos0)=1

Question 54

What is the power factor in a pure inductive or capacitive circuit? A. 0 B. -1 C. Infinity

Answer 54

A. 0 A circuit which contains only inductance is called a pure inductive circuit and a circuit containing only a pure capacitor is known as a pure capacitive circuit. In a pure inductive circuit or a pure capacitive circuit, the current is lagging or ahead by 90 degrees from the voltage. The power factor is the cosine of the angle between the voltage and the current. Therefore: Φ=π2 - Power factor (cosn2)=0

Question 55

Which of the following is true about power factor? A. cosΦ = True power /Apparent power B. cosΦ = Apparent power/ True power C. sinΦ = True power / Apparent power

Answer 55

A. cosΦ = True power /Apparent power The power factor of an AC electrical power system is defined as the ratio of the real or true power absorbed by the load to the apparent power flowing in the circuit, and in the closed interval of -1 to 1. The expression for power factor is given as: cosΦ = True power / Apparent power

Question 56

Power factor of an inductive circuit is usually improved by adding a capacitor to it in A. Either series or parallel B. None of these choices C. Parallel D. Series

Answer 56

A. Either series or parallel

Question 57

For a given wirewound core, an increase in current through the coil A. increases the flux density B. decreases the flux density C. reverses the flux lines D. causes no change in flux density

Answer 57

A. increases the flux density

Question 58

When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage A. reaches zero B. remains constant C. decreases D. increases

Answer 58

D. increases

Question 59

What are the effects of moving a closed wire loop through a magnetic field? A. A current is induced in the wire B. All of these choices C. The polarity across the wire depends on the direction of motion. D. A voltage is included in the wire

Answer 59

B. All of these choices

Question 60

If a conductor is horizontal, the current flowing from left to right and the direction of the surrounding magnetic field is from above to below, the force exerted on the conductor is. A. from left to right B. towards the viewer C. away from the viewer D. from below to above

Answer 60

C. away from the viewer

Question 61

Magnetic flux can always be attributed to: A. Ferromagnetic materials B. The geomagnetic field C. Motion of charged particles

Answer 61

C. Motion of charged particles

Question 62

When the current through an inductor is cut in half, the amount of energy stored in the electromagnetic field? A. doubles B. does not change C. is quartered D. quadruples

Answer 62

C. is quartered

Question 63

Which of the following symbol denotes magnetic field intensity? A. B B. mmf C. H

Answer 63

C. H B= flux density mmf = magnetomotive force H= magnetic field intensity

Question 64

Which of the following statements is/ are true? P: hard magnetic material has high remanence Q: hard magnetic material has large coercivity A. Q only B. neither P nor Q C. P only D. both P and Q

Answer 64

D. both P and Q Hard magnetic material has high remanence and large coercivity making them difficult to demagnetize.

Question 65

What is the name for a non-metallic material that has the ferromagnetic properties of iron? A. toroid B. solenoid C. ferrite D. lodestone

Answer 65

C. ferrite Ferrites are ceramic-like materials with magnetic properties that are useful in many types of electronic devices.

Question 66

Anderson bridge is a modification of ___ bridge. A. Maxwell-Wien B. Hay's C. Owen

Answer 66

A. Maxwell-Wien

Question 67

The force between a magnet and a piece of ferromagnetic metal that has not been magnetized: A. Is never repulsive B. Can be either repulsive or attractive C. Gets smaller as the magnet gets closer to the metal D. Depends on the geomagnetic field

Answer 67

A. Is never repulsive

Question 68

What is the unit for relative permeability? A. No unit D. H-m C. H/m

Answer 68

A. No unit Relative permittivity is a unitless quantity since it is a ratio of permeability and absolute permeability that are both expressed in H/m.

Question 69

A permanent magnet would most likely be made from: A. brass B. copper C. aluminum D. steel

Answer 69

D. steel

Question 70

The phenomenon of perfect diamagnetism is called ___ A. Meissner Effect B. Zero Kelvin Effect C. Diamagnetic Effect D. Superconductivity

Answer 70

A. Meissner Effect The phenomenon of perfect diamagnetism in superconductors is called the Meissner effect, after the name of its discoverer. It is used to magnetically levitate superfast trains.

Question 71

Which of the following statements about a three-phase squirrel-cage induction motor is false? A. It has no external electrical connections to its rotor B. A magnetic flux which alternates is produced C. It has no external electrical connections to its rotor D. It is cheap, robust and requires little or no skilled maintenance

Answer 71

B. A magnetic flux which alternates is produced

Question 72

The slip speed of an induction motor: A. is zero until the rotor moves and then rises to 100 per cent B. is 100 per cent until the rotor moves and then decreases slightly C. is 100 per cent until the rotor moves and then falls to a low value

Answer 72

C. is 100 per cent until the rotor moves and then falls to a low value

Question 73

Refer to a three-phase induction motor. Which statements are false? A. The slip speed is the synchronous speed minus the rotor speed B. The torque on the rotor is due to the interaction of magnetic fields C. As the rotor is loaded, the slip decreases D. The torque on the rotor is due to the interaction of magnetic fields

Answer 73

C. As the rotor is loaded, the slip decreases

Question 74

The slip speed of an induction motor depends upon: A. eddy currents B. supply voltage C. mechanical load

Answer 74

C. mechanical load

Question 75

Electric motors works on the principle of A. couple B. friction C. capacitors D. torque

Answer 75

D. torque

Question 76

The slip speed of an induction motor may be defined as the: A. number of pairs of poles ÷ frequency B. rotor speed - synchronous speed C. synchronous speed - rotor speed

Answer 76

C. synchronous speed - rotor speed

Question 77

How should the winding axes of solenoid inductors be placed to minimize their mutual inductance? A. In line B. At right angles C. Parallel to each other D. Interleaved

Answer 77

B. At right angles

Question 78

An LR-C parallel circuit has the following component values: R = 100, L= 10mH,C=10 μF and V= 100 V. Which of the following statements is false? A. The circuit Q-factor at resonance is 30 B. The dynamic resistance is 1000 C. The current at resonance is 1A D. The resonant frequency fr is 1.5/π kHz

Answer 78

A. The circuit Q-factor at resonance is 30

Question 79

In a highly capacitive circuit A. Reactive power is more than the apparent power B. Apparent power is equal to the actual power C. Reactive power is more than the actual power D. Actual power is more than its reactive power

Answer 79

C. Reactive power is more than the actual power

Question 80

What is the power factor for a series LCR circuit at resonance? A. -1 B. Infinity C. 1

Answer 80

C. 1 At resonance, XL=Xc →Z=R; So, the total impedance of the circuit is only due to resistor. The phase angle between voltage and current is zero. Therefore, Φ=OPower factor (cosΦ)=1

Question 81

Pure inductive circuit A. Does not take power at all from a line B. Takes power from the line during some part of the cycle and then returns back to it during other part of the cycle C. None of these choices

Answer 81

B. Takes power from the line during some part of the cycle and then returns back to it during other part of the cycle

Question 82

In AC circuit the power curve is a sine wave having A. Three times the frequency of the voltage B. Same frequency as that of voltage C. Double the frequency of voltage

Answer 82

C. Double the frequency of voltage

Question 83

The power factor of practical inductor is A. Unity B. Leading C. Lagging D. Zero

Answer 83

C. Lagging

Question 84

When an alternating current passes through an ohmic resistance the electrical power converted into heat is A. True power B. None of these choices C. Reactive power

Answer 84

A. True power

Question 85

A material that can be permanently magnetized is generally said to be. A. Ferromagnetic. B. Magnetic. C. Permanently magnetic. D. Electromagnetic.

Answer 85

A. Ferromagnetic.

Question 86

For the circuit shown in the figure, the internal resistance r is given by: (REM A ELEX LVL 1,2,3 FIGURE) A. 1/E-V B. I/V-E C. V-E/I D. E-V/I

Answer 86

C. V-E/I

Question 87

The only inductive circuit takes power from the AC mains when A. Applied voltage decreases but current increases B. Both applied voltage and current decrease C. Applied voltage decreases but current decreases

Answer 87

A. Applied voltage decreases but current increases

Question 88

A pure capacitance is connected across 50 HZ, 230 V supply consumes 0.04 W.This consumption is attributed to A. Ohmic loss due to ohmic resistance of plates B. Loss of energy in dielectric C. Both Ohmic loss due to ohmic resistance of plates and Loss of energy in dielectric D. Capacitive reactance in ohms

Answer 88

A. Ohmic loss due to ohmic resistance of plates

Question 89

An alternator is delivering power to a balanced load at unity power factor. The phase angle between the line voltages and the line current is A. 0° B. 60° C. 30°

Answer 89

C. 30°

Question 90

In a three-phase supply, floating neutral is undesirable because it may result in.......across the load. A. None of these Choices B. High voltage C. Unequal line voltages

Answer 90

C. Unequal line voltages

Question 91

The power factor of an ordinary electric bulb is A. Unity B. Slightly more than unity C. Zero D. Slightly less than unity

Answer 91

D. Slightly less than unity

Question 92

To improve the power factor in three phase circuits, the capacitor bank is connected in Delta to make A. The power factor correction more effective B. The connection elegant C. Capacitance very small

Answer 92

C. Capacitance very small