Electrical Objective Flashcards by Evelyn Yap

What is the process of heating electrically non-mettalic materials such as plumbers,
plastics, etc

A. Resistive
B. Capacitive
C. Dielectric
D. Induction

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How are multiple stop push buttons connected in a control circuit

A. Series-parallel
B. Parallel
C. Gang
D. Series

D. Series

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In series circuit when the voltage remains constant and the resistance increases, the current ________.

A. remains the same
B. decreases
C. increases
D. increases by the square

B. Decreases

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An overcurrent trip unit if a circuit shall be connected in series with each ________.

A. grounded conductor
B. overcurrent device
C. transformer
D. ungrounded conductor

D. Ungrounded conductor

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The rating of the largest size regular plug fuse is ____ amperes.

A. 20
B. 15
C. 60
D. 30

D.30

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Multiple start buttons in a motor control circuit are connected in _____.

A. none of these
B. parallel
C. series-parallel
D. series

B. Parallel

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If the end of a cartridge fuse becomes warmer than normal, you should _____.

A. notify the utility company
B. change the fuse
C. lower the voltage on the circuit
D. tighten the fuse clips

D. tighten the fuse clips

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A capacitor opposes _____.

A. change in current
B. none of these
C. change in voltage
D. change in voltage and current

C.Change in voltage

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A circuit breaker that has purposely introduced into a delay in the tripping action and which delay decreases as the magnitude of the current increases in a ____ circuit breaker.

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Branch circuit conductors shall have an ampacity not less than _____.

I. the load increased 125%
II. 100% of the load to be served
III. 80% of the load to be served
IV. 125% of the continuous load plus 80% of the non-continuous load

II only

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An SCR combines the feature of

A. Rectifier and resistance
B. Rectifier and capacitor
C. Rectifier and transistor
D. Rectifier and inductor

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What electrode in a junction transistor corresponds to the cathode in vacuum tube

A. Base
B. Emitter
C. Drain
D. Collector

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How are multiple stop push buttons connected in a control circuit

A. Series-parallel
B. Parallel
C. Gang
D. Series

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A __ is a device that carry and interrupt load current even in case of a fault by used of
separate contacts.

A. Air switch
B. Fuse
C. Sectionalizing
D. Circuit breaker

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Merz price protection is used on

A. Substations
B. Capacitor Banks
C. Induction motors
D. Generators

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Slip rings are made of

A. Steel
B. Copper
C. Bakelite
D. Mica

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For which of the following sinusoids, the rms value and mean value is the same?

A. Sine wave
B. Triangular wave
C. Square wave
D. None of the above

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For planned outages, customers or users shall be notified at least __ days prior to the loss of power.

A. 3
B. 5
C. 6
D. 10

A.3
3 for distribution side
7 for transmission side

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A generating unit providing backup reserve shall have a fast start capability and its capacity shall be sustainable for a minimum period of __ hours.

A. 5
B. 8
C. 10
D. 12

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The distributor shall design and operate its system to assist the system operator on maintaining its fundamental frequency within the limits of __ Hz to __ Hz during normal conditions.

A. 59-60
B. 59.7-60.3
C. 58.3-60.3
D. 59.3-50.3

B. 59.7-60.3

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ANSI Device No. 21

A. Distance Relay
B. Frequency Relay
C. Overcurrent Relay
D. Undervoltage Relay

A. Distance Relay

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Which of the following transformer has only one winding?

A. Current
B. Distribution
C. Autotransformer
D. Power

C. Autotransformer

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Which of the following transformer has only one winding?

A. Current
B. Distribution
C. Autotransformer
D. Power

C. Autotransformer

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For an unbalanced 3 phase load, which connection is suitable?

A. 3 wire, open delta
B. Three wire, wye
C. Four wire, wye
D. 3 wire, delta

C. Four wire, wye

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The Code rule for maximum 900 bends in a conduit between two boxes is four, the most likely reason for the total 3600 limitation is I. it is unsafe II. it makes pulling the conductors throught the conduit too difficult III. you can damage the galvanized coating on the conduit Iv. too many bends require extra wire to be pulled

II only

Hysterisis is I. the tool used to read the specific gravity of battery II. the lagging of magnetism, in a magnetic metal, behind the magnetizing flux which produces it. III. the opposition of impedance IV. none of these

II only

Fixtures supported by the framing members of suspended ceiling system shall be securely fastened to the ceiling framing memeber by mechanical meas such as _____. I. bolts or screws II. rivets III. clips identified for this use

I,II, III

A laminated pole is _____. I. one built up of layers or iron sheets,stamped from sheet metal and insulated II. used in transmission lines over 100kv III. a pole soaked in creosote IV. found in the north pole

I only

Tinning rubber insulated twisted cable is done to ____. I. make the strand stronger II. prevent chemical reaction between the copper and the rubber III. increase the resistance IV. meet NEMA requirements

II only

Insulated nonmetallic boxes are made of I. polyvinyl chloride II. bakelite III. Bower-Barff lacquer

I and II

When voltage and current appear at their zero and peak values at the same time, they are in ____. A. group B. balanced C. motion D. phase

D. phase

What refers to the ratio of thermal conductivity of a material to the product of electrical conductivity and temperature? A. Matthiessens’ ratio B. Wiedermann’s-Frantz ratio C. Conductivty ratio D. Maxwell’s ratio

B. Wiedermann’s-Frantz ratio

Copper-clad aluminum conductors have a ampacity ____. A. rating of their own B, equal to copper C. equal to aluminum D. lower than copper but higher than aluminum

C. equal to aluminum

The greatest voltage drop in a circuit will occur when the ______ the current flow through that part of the circuit. A. slower B. lower C. greater D. faster

C. greater

The usual service conditions under which a transformer should be able to carry its rated load are ____. I. at rated secondary voltage or not in excess of 105% of the rated value II. at rated frequency II. temperature of the surrounding cooling air at no time exceeding 400C and average temperatir of the surrounding cooling ari during any 24 hour period not exceeding 300 C

I , II , III

When installing an instrument meter on a panel, to obtain accurate mounting _____. A. drill oversize holes B. drill from back of the panel C. use the meter and drill through the holes D. use a template

D. use a template

Never approach a victim of an electrical injury until you ____. A. find a witness B. contact the supervisor C. have a first-aid kit D. sure the power is turned off

D. sure the power is turned off

One commercial unit of energy equals A. 500 watt-seconds B. One watt-hour C. One kilowatt-hour D. ten kilowatt-hour

C. 1kwh

Whenever a conductor cuts magnetic flux, an emf is induced in that conductor. Above statement is due to A. Joule's law B. Coulomb's law C. Faraday's law D. Weber and Ewing's theory

In an RLC circuits, the impedance at resonance is A.maximum B. infinity C. minimum D.zero

A 60 Hz frequency would cause an electric light to A.turn on and off 120 times per second C. flicker noticeable B.turn on and off 180 times per second D. turn on and off 60 times per second

In the left hand rule, thumbs always represent A.Voltage B. Direction of force on conductor C. Current D. Magnetic field

In gases flow of current is due to A. electrons only C. positive ions only B. electrons and positive ions D. electrons positive ions and negative ions

Copper wire of certain length and resistance is drawn out to three times its length without change in volume, the new resistance of wire becomes A. 1/9 times B. 3 times C. 9 times D. unchanged

In an electric kettle water boils in 10 minutes. It is required to boil the boiler in 15 minutes, using same supply mains A. length of heating element should be decreased B. length of heating element should be increased C. length of heating element has no effect on heating if water D, none of the above

The S.I. unit of power is A. henry B. coulomb C. watt D. watt-hour

The flow of current in solids is due to A. electrons B. electrons and ions C. atoms D. nucleus

How can inductance of the coil can be increased? A. By increasing the current B. By connecting ohmic resistance in series C. By thick layers of hard paper in the gap D. By increasing the number of turns

One coulomb charge equal the charge on A. 6.24 x 10^12 electrons B. 6.24 × 10^14 electrons C. 6.24 × 10^12 electrons D. 6.24 x 10^18 electrons

The property of a conductor due to which it passes current is called A. resistance B. reluctance C. conductance D. inductance

Conductance is reciprocal of A. resistance B. inductance C. reluctance D. inductance

The resistance of a conductor varies inversely as A. length B. temperature C. resistivity D. area of cross-section

With rise in temperature the resistance of pure metals A. increases C. first increases and then decreases B. decreases D. remains constant

In the case of an unsymmetrical alternating current the average value must always be taken over A. unsymmetrical part of the wave form C.the half cycle B. the quarter cycle D. the whole cycle

Which of the following material has nearly zero temperature co-efficient of resistance? A. Manganin B. Porcelain C. Carbon D. Copper

Two resistors are said to be connected in series when A. same current passes in turn through both C. both carry the same value of current B. total current equals the sum of branch currents D. sum of IR drops equals the applied e.m.f.

Which of the following materials has a negative temperature co-efficient of resistance? A. Copper B. Aluminum C. Carbon D. Brass

Ohm's law is not applicable to A. vacuum tubes C. high voltage circuit D. circuits with low current densities B. carbon resistor

According to Kirchhoff's voltage law, the algebraic sum of all IR drops and e.m.fs, in any closed loop of a network is always A. negative B. positive C. determined by battery e.m.fs. D. zero

The concept on which Superposition theorem is based is A. reciprocity B. duality C. non-linearity D. linearity

Thevenin resistance Rth is found A. by removing voltage sources along with their internal resistances B. by short-circuiting the given two terminals C. between any two 'open' terminals D. between same open terminals as for Eth

"Any number of current sources in parallel may be replaced by a single current source whose current is the algebraic sum of individual source currents and source resistance is the parallel combination of individual source resistances". The above statement is associated with A. Thevenin's theorem C. Maximum power transfer theorem B. Millman's Theorem D. None of the above

"In any network containing more than one sources of emf the current in any branch is the algebraic sum of a number of individual fictitious currents ( the number being equal to the number of sources of emf), each of which is due to separate action of each source of emf, taken in order, when the remaining sources of emf are replaced by conductors, the resistances of which are equal to the internal resistances of the respective sources". The above statement is associated with A. Thevenin's theorem C. Superposition theorem B. Norton's theorem D. None of the above

If the circuit does not contain any source of energy or emf it is known as A. unilateral circuit B. bilateral circuit C. passive network D. active network

The circuit has resistors, capacitors and semi-conductor diodes. The circuit will be known as A. bilateral circuit B. non-linear circuit C. linear circuit D. none of the above

Electric pressure is also called A. resistance B. power C. voltage D. energy

The substances which have a large number of free electrons and offer a low resistance are called A insulator B. inductors C. semi-conductors D. conductors

Out of the following which is not poor conductor? A. Cast iron B. Copper C. Carbon D. Tungsten

Two wattmeter can be used to measure 3-phase power for a A. balanced and unbalanced load C. unbalanced load only B.balanced load only D. unity power factor only

Out of the following which is an insulating material? A. Copper B. Gold C. Silver D. Paper

For which of the following parameter variation, the capacitance of the capacitor remains unaffected? A. Distance between plates C. Nature of dielectric B. Area of the plates D. Thickness of the plates

Fleming's left hand rule is used to find A. direction of magnetic field due to current carrying conductor B. direction of flux in a solenoid C. direction of force on a current carrying conductor in a magnetic field D. polarity of magnetic pole

A material which is slightly repelled by a magnetic field is known as A. ferromagnetic material B. diamagnetic material C. paramagnetic material D. conducting material

Conductivity is analogous to A. retentivity B. resistivitv C. permeability D. inductance

Both the number of turns is the core lengths of an inductive coil are doubled. Its self-inductance Will be A. unaffected B. doubled C. halved D. quadrupled

For the series RL circuit at resonance the current amplitude is for a fixed voltage amplitude and power factor is A.minimum, zero B. maximum, zero C. minimum, unity D. maximum, unity

Which of the following statement is true both for series and a parallel DC circuit? A. elements have individual currents C. currents are additive C. voltages are additive D. power are additive

Lenz's law is a consequence of the law of conservation of A. induced current B. charge C. energy D. induced emf

In a star connected system, the line current is A.0.707 times the phase current B.equal to the phase current C. 1.732 times the phase current D. 1.414 times the phase current

In a pure resistive circuit A. current lags behind the voltage by 90° B. currents lead the voltage by 90° C. current can lead or lag the voltage by 90° D. current is in phase with the voltage

"Maximum power output is obtained from a network when the load resistance is equal to the output resistance of the network as seen from the terminals of the load". The above statement is associated with A. Millman's theorem B. Thevenin's theorem C. Superposition theorem D. Maximum power transfer theorem

In a three-phase supply floating neutral is undesirable because it way give rise to A. high voltage across the load B. low voltage across the load C. unequal line voltages across the load D. none of the above

A series R-L-C circuit draws current at leading power factor at A. more than resonant frequency' C. resonant frequency B. less than resonant frequency D. none of the above

The draft velocity of electrons is A. a very small as compared to speed of light C. equal to speed of light B. almost equal to speed of light D. greater than speed of light

An instrument which detects electric current is known as A. voltmeter B. rheostat C. wattmeter D. galvanometer

"In any linear bilateral network, if a source of emf E in any branch produces a current / in any other branch, then same emf acting in second branch would produce the same current / in the first branch". The above statement is associated with A. compensation theorem B. superposition theorem C. reciprocity theorem D. none of the above