Basic Electrical Engineering

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[1] Which of the following can vary with ac, but never with dc?

1 point

A. Power

B. Voltage

C. Frequency

D. Amplitude

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[2] If all other factors are kept constant, the inductance of the air-core coil is not affected by

1 point

A. The frequency

B. The number of turns

C. The diameter of the coil

D. The length of the coil

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[3] The length of time between a point in one cycle and the same point in the next cycle of an ac wave is the

1 point

A. Frequency

B. Magnitude

C. Period

D. Polarity

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[4] Capacitance acts to store electrical energy as

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A. Current

B. Voltage

C. A magnetic field

D. An electric field

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[5] On a spectrum analyzer, a ac signal having only one frequency component looks like

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A. A single pip

B. A sine wave

C. A square wave

D. A sawtooth wave

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[6] A ferromagnetic core is place in the inductor to

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A. Increase the current carrying capacity

B. Increase the inductance

C. Limit the current

D. Reduce the inductance

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[7] The period of a ac wave, in seconds is

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A. The same as the frequency in hertz

B. Not related to the frequency in any way

C. Equal to 1 divided by the frequency in hertz

D. Equal to the peak amplitude in volts divided by the frequency in hertz

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[8] An inductor works by

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A. Charging a piece of wire

B. Storing energy as a magnetic field

C. Choking off dc

D. Introducing resistance into a field

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[9] As capacitor plate area increases

1 point

A. The capacitance increases

B. The capacitance decreases

C. The capacitance does not change

D. The current handling ability decreases

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[10] In a small inductance

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A. Energy is stored and released slowly

B. The current flow is always large

C. The current flow is always slow

D. Energy is stored and released quickly

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[11] In ac circuit, the ratio of kW/kVA is

1 point

A. power factor

B. form factor

C. load factor

D. diversity factor

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[12] Suppose that two ac waves have the same frequency but differ in phase by exactly 1/20 of a cycle. Whatis the phase difference between these two waves?

1 point

A. 18 deg

B. 20 deg

C. 36 deg

D. 5.73 deg

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[13] The unit of inductance is

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A. Mho

B. henry

C. ohm

D. farad

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[14] What is the angular frequency of the ac signal having a frequency of 1770Hz

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A. 1770 rad/s

B. 11,120 rad/s

C. 282 rad/s

D. Data insufficient

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[15] Thevenin's equivalent circuit consists of

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A. series combination of Rth, Eth, Rl

B. series combination of Rth, Eth

C. parallel combination of Rth, Eth, Rl

D. parallel combination of Rth, Eth

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[16] The frequency of DC supply is

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A. 16 2/3 Hz

B. 60 Hz

C. 50 Hz

D. 0 Hz

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[17] Load factor is defined as the ratio of

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A. max demand/ average demand

B. average demand/ connected load

C. average demand/ max. demand

D. connected load/ max demand

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[18] Q factor of an inductive coil is given by

1 point

A. 2π fL/R

B. 2π fr/R

C. R/Z

D. lr/l

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[19] The rms value of sinusoidal 100V peak to peak is

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A. 100 V

B. 50/√2 V

C. 50 V

D. 100/√2 V

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[20] Which of the following bulbs will have the least resistance?

1 point

A. 220V, 60W

B. 220V, 100W

C. 115V, 60W

D. 115V, 100W

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[21] The wire is stretched to double its length, then its resistance R will become

1 point

A. r/2

B. 4r

C. 2r

D. r/4

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[22] The power drawn by the circuit whose input is 20KVA and p.f is 0.8 lagging

1 point

A. 12

B. 20

C. 16

D. 8

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[23] The combined resistance of two equal resistors connected in parallel is equal to

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A. One half the resistance of one resistor

B. twice the resistance of one resistor

C. four times the resistance of one resistor

D. one fourth the resistance of one resistor

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[24] The superposition theorem is applicable to circuits only having ............ elements

1 point

A. non-linear

B. passive

C. resistive

D. linear bilateral

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[25] The Q-factor of a coil is given by

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A. its power factor

B. Ratio of max. energy stored & energy dissipated per cycle.

C. reciprocal of its power factor

D. ratio R/Z

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[26] The power factor at resonance in RLC circuit is

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A. zero

B. unity

C. 0.5 lagging

D. 0.5 leading

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[27] Cells are connected in parallel to

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A. Increase the available voltage

B. Reduce the cost of wiring

C. Increase the available current

D. Reduce the time required to fully charge them after use

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[28] the power factor of a purely resistive circuit is

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A. zero

B. unity

C. lagging

D. leading

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[29] Which of the following has minimum running cost?

1 point

A. Hydro electric station

B. nuclear power station

C. thermal power station

D.diesel power station

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[30] The color code of a resistor 2.7Kohm with the tolerance of 10% is

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A. red, violet, red and silver

B. red, violet, yellow and gold

C. red, violet, orange, silver

D. red, violet, red, gold

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[31] In a 117Vrms utility circuit, the peak-to-peak voltage is approximately

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A. 82.7 V

B. 165 V

C. 234 V

D. 331 V

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[32] Watt-hour is the unit of

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A. Electric power

B. Electric capacity

C. Electric energy

D. Electric charge

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[33] In India,electrical power is transmitted by

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A. 1-phase ac system

B. 3-wire dc system

C. 3-phase 3-wire ac system

D. 2 wire dc system

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[34] If two perfect sine waves have the same frequency and the same phase, the composite wave

1 point

A. Is a sine wave with an amplitude equal to the difference between the amplitude of the waves

B. Is a sine wave with an amplitude equal to the sum of the amplitudes of the two original

waves

C. Is not a sine wave, but has the same frequency as the two input waves

D. Has zero amplitude (ie, it does not exist) because the two input waves cancel each other out.

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[35] In a ac circuit the product of voltage and current is known as

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A. Power

B. Real Power

C. Resistive power

D. Apparent power

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[36] The advantage of AC over DC in utility applications is

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A. AC is easier to transform from one voltage to another

B. AC is transmitted with lower loss in wires

C. AC can be easily obtained from dc generators

D. AC can be generated with less dangerous by products

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[37] A network that does not have either voltage or current source is called ......network

1 point

A. Active

B. Passive

C. Resistive

D. Dummy

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[38] The sixth harmonic of a ac wave whose period is 1 Milli second has a frequency of

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A. 0.006Hz

B. 167.0 Hz

C. 7.0 kHz

D. 6 kHz

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[39] A degree of phase represents

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A. 6.28 cycles

B. 57.3 cycles

C. 1/60 of a cycle

D. 1/360 of a cycle

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[40] A battery is source of

1 point

A. DC voltage

B. 1 phase AC voltage

C. 3 phase ac voltage

D. ac or dc voltage

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[41] The power plant having highest efficiency is

1 point

A. Hydro

B. Thermal

C. Nuclear

D. Diesel

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[42] As the spacing between plates in a capacitor is made smaller

1 point

A. The capacitance increases

B. The capacitance decreases

C. The capacitance does not change

D. The resistance increases

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[43] The relationship between frequency and time period of ac waveform is

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A. f = T

B. f = 1/ T2

C. f = 1/T

D. f = T2

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[44] The five 0.050uF capacitors are connected in parallel. The equivalent capacitance is

1 point

A. 0.010 uf

B. 0.25 uf

C. 0.50uf

D. 0.025uf

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[45] The current gain of a bipolar transistor drops at high frequencies because of

1 point

A. Transistor capacitance

B. High current effects in the base

C. Parasitic inductive elements

D. the early effect

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[46] If two perfect sine waves have the same frequency and the same amplitude, but are in opposite phase,the composite wave

1 point

A. Has twice the amplitude of either input wave alone

B. Has half the amplitude of either input wave alone

C. Is complex, but has the same frequency as the originals.

D. Has zero amplitude ( that is, it does not exist) because the two input waves cancel each other out

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[47] Three capacitors are connected in series having capacitance of 8uF, 32uF, 16uF, the total capacitance is

1 point

A. 32/7 uF

B. 7.32 uF

C. 56 uF

D. 32 uF

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[48] Which one of the following does not affect the power output available from a particular ac generator?

1 point

A. The strength of the magnet

B. The number of turns in the coil

C. The type of natural energy source used

D. The speed of rotation of the coil or magnet

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[49] Which of the following are active components

1 point

A. resistor and inductor

B. Diode, BJT, FET

C. Opamp, BJT, thermionic triode

D. Capacitor, Inductor

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[50] The energy required to charge a 10 uF capacitor to 100V is

1 point

(a) 0.10 J

(b) 0.05 J

(d) 10 X 10-9 J

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