Electrical Engineering Basics Objective Questions with Answers: Part-17

Electrical Engineering Basics Objective Questions with Answers

[1] Electrostatics is a branch of electricity concerned with
(a) Energy flowing across a gap between conductors
(b) Charges at rest
(c) Charges in motion
(d) Energy in the form of charges

Answer: B

[2] Four 2 μF capacitors are connected in series. The equivalent capacitance is
(a) 8 μF
(b) 0.5 μF
(c) 2 μF
(d) 6 μF

Ans: B

[3] State which of the following is false.
The capacitance of a capacitor
(a) Is proportional to the cross-sectional area of the plates
(b) Is proportional to the distance between the plates
(c) Depends on the number of plates
(d) Is proportional to the relative permittivity of the dielectric

Ans: B

[4] The capacitance of a capacitor is the ratio
(a) Charge to potential difference between plates
(b) Potential difference between plates to plate spacing
(c) Potential difference between plates to thickness of dielectric
(d) Potential difference between plates to charge

Ans: A

[5] Which of the following statement is false?
(a) An air capacitor is normally a variable type
(b) A paper capacitor generally has a shorter service life than most other types of
capacitor
(c) An electrolytic capacitor must be used only on a.c. supplies
(d) Plastic capacitors generally operate satisfactorily under conditions of high temperature

Ans:A

[6] The potential difference across a 10 μF capacitor to charge it with 10mC is
(a) 10V
(b) 1 kV
(c) 1V
(d) 10V

Ans: B

[7] The energy stored in a 10μF capacitor when charged to 500V is
(a) 1.25 mJ
(b) 0.025 μJ
(c) 1.25 J
(d) 1.25 C

Ans: C

[8] The capacitance of a variable air capacitor is at maximum when
(a) The movable plates half overlap the fixed plates
(b) The movable plates are most widely separated from the fixed plates
(c) Both sets of plates are exactly meshed
(d) The movable plates are closer to one side of the fixed plate than to the other

Ans: C

[9] The unit of magnetic flux density is the:
(a) Weber
(b) Weber per metre
(c) Ampere per metre
(d) Tesla

Ans: D

[10] The charge on a 10 pF capacitor when the voltage applied to it is 10 kV is
(a) 100 μC
(b) 0.1 C
(c) 0.1 μC
(d) 0.01 μC

Ans: C

[11] Four 2 μF capacitors are connected in parallel. The equivalent capacitance is
(a) 8 μF
(b) 0.5 μF
(c) 2 μF
(d) 6 μF

Ans: A

[12] In a series a.c. circuit the voltage across a pure inductance is 12V and the voltage across a pure resistance is 5V. The supply voltage is
(a) 13V
(b) 17V
(c) 7V
(d) 2.4V

Ans: A

[13] Inductive reactance results in a current that
(a) Leads the voltage by 90deg
(b) Is in phase with the voltage
(c) Leads the voltage by π rad
(d) Lags the voltage by π/2 rad

Ans: D

[14] A 10Ω resistor is connected in parallel with a 15 Ω resistor and the combination in series with a 12 Ω resistor. The equivalent resistance of the circuit is:
(a) 37Ω
(b) 18 Ω
(c) 27 Ω
(d) 4 Ω

Ans: B

[15] The equivalent resistance when a resistor of (1/3)Ω is connected in parallel with a (1/4)Ω resistance is:
(a) 1/7 Ω
(b) 7Ω
(c) 1/12 Ω
(d) 3/4 Ω

Ans: A

The solutions with explanations for the problems are given in the link: Part-17 Problems and solutions
Thanks for reading.. Please leave your comments below...

Posted by Unknown 7:56 AM

Multiple Choice Questions [MCQ] on Basic Electrical Engineering -Part16

Objective Type Questions on Basic Electrical Engineering -Part16

[1]  A 240V, 60W lamp has a working resistance of:
(a) 1400Ω
(b) 60Ω
(c) 960Ω
(d) 325Ω

Ans: C

[2] The symbol for the unit of temperature coefficient of resistance is:
(a) Ω /°C
(b)Ω
(c) °C
(d) Ω /Ω°C

Ans: D

[3] The length of a certain conductor of resistance 100Ω is doubled and its cross-sectional area is halved. Its new resistance is:
(a) 100Ω
(b) 200Ω
(c) 50Ω
(d) 400Ω

Ans: D

[4] Voltage drop is the:
(a) Maximum potential
(b) Difference in potential between two points
(c) Voltage produced by a source
(d) Voltage at the end of a circuit

Ans: B

[5] The largest number of 100W electric light bulbs which can be operated from a 240V supply fitted with a 13A fuse is:
(a) 2
(b) 7
(c) 31
(d) 18

Ans: C

[6] When an atom loses an electron, the atom:
(a) Becomes positively charged
(b) Disintegrates
(c) Experiences no effect at all
(d) Becomes negatively charged

Ans: A

[7] The energy used by a 1.5kW heater in 5 minutes is:
(a) 5 J
(b) 450 J
(c) 7500 J
(d) 450 000 J

Ans: D

[8] The unit of resistivity is:
(a) ohms
(b) ohm millimetre
(c) ohm metre
(d) ohm/metre

Ans: C

[9] A resistor marked as4K7G indicates a value of:
(a) 47Ω ±20%
(b) 4.7Ω k ±20%
(c) 0.47Ω ±10%
(d) 4.7 kΩ ±2

Ans: D

[10] The resistance of a 2 km length of cable of cross-sectional area 2mm² and resistivity of 2×10^-8Ω m is:
(a) 0.02Ω
(b) 20Ω
(c) 0.02mΩ
(d) 200Ω

Ans: B

[11] A piece of graphite has a cross-sectional area of 10mm². If its resistance is 0.1Ω and its resistivity 10×10⁸ Ωm, its length is:
(a) 10 km
(b) 10 cm
(c) 10 mm
(d) 10 m

Ans: D

[12] A nickel coil has a resistance of 13Ω at 50°C. If the temperature coefficient of resistance at 0°C is 0.006/ °C, the resistance at 0°C is:
(a) 16.9Ω
(b) 10Ω
(c) 43.3Ω
(d) 0.1Ω

Ans: B

[13] A coil of wire has a resistance of 10 at 0°C. If the temperature coefficient of resistance for the wire is 0.004/ °C, its resistance at 100°C is:
(a) 0.4Ω
(b) 1.4Ω
(c) 14Ω
(d) 10Ω

Ans: C

[14] A colour coding of red-violet-black on a resistor indicates a value of:
(a) 27Ω ±20%
(b) 270Ω
(c) 270Ω ±20%
(d) 27Ω ±10%

Ans: C

[15] An inductance of 10mH connected across a 100V, 50 Hz supply has an inductive reactance of
(a) 10π
(b) 1000π
(c) π
(d) π H

Ans:C

Posted by Unknown 9:38 AM

Multiple Choice Questions [MCQ] on Basic Electrical Engineering -Part15

First year Engineering Basic Electrical Engineering Objective Questions

[1] The coulomb is a unit of:
(a) Energy
(b) Voltage
(c) Power
(d) Quantity of electricity

Ans: D

[2] A charge of 240 C is transferred in 2 minutes. The current flowing is:
(a) 480A
(b) 120A
(c) 2A
(d) 8A

Ans: C

[3] A resistance of 50 kΩ has a conductance of:
(a) 20S
(b) 0.02S
(c) 0.02 mS
(d) 20 kS

Ans: C

[4] Which of the following statements is incorrect?
(a) 1N = 1 kgm/s²
(b) 1V = 1 J/C
(c) 30mA = 0.03A
(d) 1 J = 1N/m

Ans:D

[5] The power dissipated by a resistor of 10 ohm when a current of 2A passes through it is:
(a) 0.4W
(b) 20W
(c) 40W
(d) 200W

Ans: C

[6] A mass of 1200g is accelerated at 200 cm/s² by a force. The value of the force required is:
(a) 2.4N
(b) 2400N
(c) 240 kN
(d) 0.24N

Ans: A

[7] A current of 2A flows for 10 hour through a 100 ohm resistor. The energy consumed by the resistor is:
(a) 0.5 kWh
(b) 4 kWh
(c) 2 kWh
(d) 0.02 kWh

Ans:B

[8] The unit of quantity of electricity is the:
(a) volt
(b) coulomb
(c) ohm
(d) joule

Ans: B

[9] Electromotive force is provided by:
(a) Resistance’s
(b) A conducting path
(c) An electric current
(d) An electrical supply source

Ans: C

[10] The unit of current is the:
(a) Volt
(b) Coulomb
(c) Joule
(d) Ampere

Ans: D

[11] In order that work may be done:
(a) Two wires are necessary
(b) The circuit must have a switch
(c) Coal must be burnt
(d) A supply of energy is required

Ans: D

[12] The ohm is the unit of:
(a) Charge
(b) Resistance
(c) Power
(d) Current

Ans: B

[13] The unit of resistivity is:
(a) ohms
(b) ohm millimetre
(c) ohm metre
(d) ohm/metre

Ans: C

[14] Voltage drop is the:
(a) Maximum potential
(b) Difference in potential between two points
(c) Voltage at the end of a circuit
(d) Voltage produced by a source

Ans: B

[15] A 240V, 60W lamp has a working resistance of:
(a) 1400 ohm
(b) 60 ohm
(c) 960 ohm
(d) 325 ohm

Ans: C

Solution Hint:
[1] Units
Energy - Watt-hr
Voltage - volts
Power - watts
[2] Current  =  Charge in coulomb/ Time in sec
[3] Conductance = 1/Resistance
[15] P = V²/R

Thanks for reading..

Posted by Unknown 7:12 AM

Objective Questions on Batteries with Answers

Multi-Choice Questions [MCQ] with Answers from Batteries

[1] A battery consists of
(a) A cell
(b) A circuit
(c) A generator
(d) A number of cells

Answer: D

[2] The terminal potential difference of a cell of e.m.f. 2V and internal resistance 0.1Ω when supplying a current of 5A will be
(a) 1.5V
(b) 2V
(c) 1.9 V
(d) 2.5V

Answer: A

[3] Five cells, each with an e.m.f. of 2V and internal resistance of 0.5Ω are connected in series. The resulting battery will have
(a) An e.m.f. of 2V and an internal resistance of 0.5 Ω
(b) An e.m.f. of 10V and an internal resistance of 2.5 Ω
(c) An e.m.f. of 2V and an internal resistance of 0.1 Ω
(d) An e.m.f. of 10V and an internal resistance of 0.1 Ω

Answer: B

[4] If the five cells of question 3 are connected in parallel the resulting battery will have
(a) An e.m.f. of 10V and an internal resistance of 2.5 Ω
(b) An e.m.f. of 2V and an internal resistance of 0.5 Ω
(c) An e.m.f. of 2V and an internal resistance of 0.1 Ω
(d) An e.m.f. of 10V and an internal resistance of 0.1 Ω

Answer: C

[5] Which of the following statements is false?
(a) A Leclanché cell is suitable for use in torches
(b) A nickel–cadmium cell is an example of a primary cell
(c) A secondary cell may be recharged after use
(d) When a cell is being charged its terminal p.d. exceeds the cell e.m.f.

Answer: B

[6] Which of the following statements is false?
When two metal electrodes are used in a simple cell, the one that is higher in the electrochemical series:
(a) Tends to dissolve in the electrolyte
(b) Is always the negative electrode
(c) Reacts most readily with oxygen
(d) Acts an an anode

Answer:D

[7] Five 2V cells, each having an internal resistance of 0.2Ω are connected in series to a load of resistance 14 Ω. The current flowing in the circuit is
(a) 10A
(b) 1.4A
(c) 1.5A
(d) 2/3A

Answer: D

[8] For the circuit of question 7, the p.d. at the battery terminals is
(a) 10V
(b) 9(1/3)V
(c) 0V
(d) 10(2/3)V

Answer: B

[9] Which of the following statements is true?
(a) The capacity of a cell is measured in volts
(b) A primary cell converts electrical energy into chemical energy
(c) Galvanising iron helps to prevent corrosion
(d) Apositive electrode is termed the cathode

Answer: C

[10] The greater the internal resistance of a cell
(a) The greater the terminal potential difference.
(b) The less the e.m.f.
(c) The greater the e.m.f.
(d) The less the terminal potential difference.

Answer: D

[11] The negative pole of a dry cell is made of
(a) Carbon
(b) Copper
(c) Zinc
(d) Mercury

Answer: C

[12] The energy of a secondary cell is usually renewed
(a) By passing a current through it
(b) It cannot be renewed at all
(c) By renewing its chemicals
(d) By heating it

Answer: A

[13] Which of the following statements is true?
(a) A zinc carbon battery is rechargeable and is not classified as hazardous
(b) A nickel cadmium battery is not rechargeable and is classified as hazardous
(c) A lithium battery is used in watches and is not rechargeable
(d) An alkaline manganese battery is used in torches and is classified as hazardous

Answer: C

Posted by Unknown 5:49 PM

Basic Electrical objective type questions: Part-13

Electrical Objective Questions with Answers:

[1] In a uniform electric field, field lines and equipotentials [Gate 1997 ]
a) Are parallel to one another
b) Intersect at 45 deg
c) Intersect at 30 deg
d) Are orthogonal

Ans:D

[2] For a pulse transformer, the material used for its core and the possible turn ratio from primay to secondary are respectively
(a) ferrite; 20:1
(b) laminated iron; 1:1
(c) ferrite; 1:1
(d) powdered iron; 1:1

Ans: C

[3] The capacitance of a reverse biased junction of a thyristor is 20 picofarad. The charging current of this thyristor is 4mA. The limiting value
of dv/dt is .....V/uS

Ans:200

[4] When the induction motor runs at synchronous speed the voltage induced in the rotor of it is
(a) Very near input voltage to stator
(b) Slip time the input voltage
(c) Zero
(d) None of the above

Ans:C

[5] Chopper control for the DC motor provides variation in
(a) Input voltage
(b) Frequency
(c) None of the above

Ans: A

[6] While comparing SCR with BJT, which of the following is true
(a) SCR requires turn off circuit while BJT does not
(b) The voltage drop of SCR is less than BJT
(c) SCR requires a continuous gate current
(d) BJT draws continuously base current
Which of the above statements are true?
(1) a only
(2) d only
(3) a, d
(4) b, d

Common Data Questions: 7 & 8 

In the 3-phase inverter circuit shown, the load is balanced and the gating scheme is 180°-conduction mode.All the switching devices are ideal

Ans: 3

[7] The rms value of load phase voltage is [GATE2012]

a. 106.1V

b. 141.4V

c. 212.2V

d. 282.8V

Ans: B

[8] If the dc bus voltage V_d=300V, the power consumed by 3-phase load is  [GATE2012]

a. 1.5kW

b. 2.0kW

c. 2.5kW

d. 3.0kW

Ans: D

[9] The typical ratio of latching current to holding current in a 20A thyristor is [GATE 2012]

a. 5.0

b. 2.0

c. 1.0

d. 0.5

Ans: B

[10] A half-controlled single-phase bridge rectifier is supplying an R-L load. It is operated at a firing angle  α and the load current is continuous. The fraction of cycle that the freewheeling diode conducts is [GATE 2012]

a. 1/2

b. (1-α/π)

c. α/2π

d. α/π

Ans: D

[11]  For power factor correction of power systems which one is used:
(a) capacitor
(b) inductor
(c) resistors

Ans: A

[12] Which type of motor used in home ceiling fan:
(a) capacitor motor 
(b) shaded pole motor 
(c) universal motor
(SPLIT PHASE CAPACITOR MOTOR)

Ans: A

[13] Op-amp (operational amplifier) input resistance:
(a) Zero
(b) Infinity
(c) Relative resistance
(d) Same output resistance

Ans:B

[14] For an inverter op-amp, what will be the equivalent output resistance?
(a) Zero
(b) Infinity
(c) Relative forward resistance
(d) Same as the input resistance

Ans: A

Posted by admin 9:31 AM

Basic Electrical Engineering: Part-12

Basic Electrical Engineering Objective Questions

[1] Power is defined as

a) The rate at which current flows in a circuit

b) The product of voltage and resistance in a circuit

c) The rate at which energy is radiated or dissipated

d) The accumulation of energy over time

e) The amount of heat generated in a circuit.

Ans:C

[2] At the exact moment a 60Hz ac sine wave is at its positive peak voltage, the instantaneous rate of change in the voltage is

a) Large and positive

b) Small and negative

c) Large and negative

d) Small and negative

e) Zero

Ans: E

[3] A flute sounds different than a violin, even if the two instruments are played at the same pitch, because of a difference in the

a) Phase

b) Chamber length

c)  Frequency

d) Waveform

e)  Bias

Ans:D

[4] A common-collector transistor circuit is often used

a)  To provide high gain and sensitivity over a wide range of frequencies

b)  To match a high impedance to a low impedance

c)  As a high-fidelity audio power amplifier

d)  As an oscillator at microwaves frequencies

e)  As the rectifier in a dc power supply.

Ans: B

[5] The internal conductance of an ammeter is generally

a)  Low

b)  Directly proportional to the current

c)  Inversely proportional to the current

d)  High

e)  Any value. It doest matter

Ans: D

[6] A steady magnetic field can be produced by

a)  A straight wire carrying a constant direct current.

b)  A loop of wire carrying a constant direct current.

c)  A coil of wire carrying a constant direct current.

d)  A constant-intensity stream of protons in free space, moving in a straight line.

e)  Any of the above.

Ans:E

[7] The output wave of a common-gate amplifier circuit with a pure sine-wave input

a)  Is in phase with the input wave.

b)  Lags the input wave by 90° of phase.

c)  Leads the input wave by 90° of phase.

d)  Is 180° out of phase with the input wave.

e)  Is inverted with respect to the input wave.

Ans:A

[8] Which of the following capacitor types is polarized?

a)  Electrolytic

b)  Paper

c)  Ceramic

d)  Mica

e)  Air variable

Ans: A

[9] when a non zero net reactance exists in an ac circuit, the apparent power is

a)  Zero

b)  Equal to the true power

c)  Less than the true power

d)  Greater than the true power

e)  Infinite

Ans: D

[10] The gauss is a unit of

(a) Charge carrier flow speed.

(b) Magnetic flux density.

(c) Electrostatic field strength.

(d) Electromagnetic field intensity.

(e) Electrical charge quantity.

Ans:B. Exp: In SI system the unit is tesla(T). In CGS system the unit is Gauss

[11] An average responding rectifier type electronic ac voltmeter has its scale calibrated in terms of the rms value of a sine wave, when a square wave voltage of peak magnitude 100V is measured using this voltmeter then the reading indicated by the meter, will be ?
a) 111V
b) 100V
c) 90.09V
d) 70.7V

Ans:B

[12] A house served by a 220V supply light, is protected by a 9-Ampere fuse. The maximum number of 60 W bulbs in parallel that can be turned on is
a) 11
b) 33
c) 22
d) 44

Ans: B

[13] Silicon has a preference in IC technology because
(a) It is an indirect semiconductor
(b) It is a covalent semiconductor
(c) It is an elemental semiconductor
(d) Of the availability of nature oxide SiO

Ans:D

[14] Three equal resistance of magnitude 5 Ohm each are connected in delta. The resistance between any two pair of terminals of the delta will be
(a) 5 Ohm 
(b) 5/3 Ohm
(c) 10/3 Ohm 
(d) 3/5 Ohm

Ans: C

[15] The R.M.S. value of a half wave rectified sinusoidal alternating current with peak value Im is
(a) Im / 1 

(b) Im / v2

(c) Im / 2 
(d) Im v3
Answer: c)

Ans: C

Posted by admin 8:58 AM

Basic Electrical Engineering: Part-11

Basic Electrical Engineering Objective Questions

[1] The unit which indicates the rate at which energy is expended?
A. Watt
B. Ampere-hour
C. Coulomb
D. Volt

Ans:A

[2] The peak voltage in an ac wave is always
A. Greater than the average voltage
B. Less than the average voltage
C. Greater than or equal to average voltage
D. Less than or equal to the average voltage

Ans: C

[3] When an electrical charge exists but there is no flow of current, the charge is said to be
A. Ionizing
B. Electronic
C. Static
D. Atomic

Ans: C

[4] As the number of turns in a coil that carries ac increases without limit, the current in the coil will
A. Eventually become very large
B. Stay the same
C. Decrease, approaching zero
D. Be stored in the core material

Ans: C

[5] As the number of turns in a coil increases, the reactance at a constant frequency
A. Increases
B. Decreases
C. Stays the same
D. Is stored in the core material

Ans:A

[6] In an RL circuit, as the ratio of inductive reactance to resistance (XL/R) decreases, the phase angle
A. Increases
B. Decreases
C. Stays the same
D. Becomes alternately positive and negative

Ans: B

[7] The best filter for a power supply is
A.  A capacitor in series
B.  A choke in series
C.  A capacitor in series and a choke in parallel
D.  A capacitor in parallel and a choke in series

Ans: D

[8] Voltage regulation can be achieved by a zener diode connected in
A.  Parallel with the filter output, forward biased
B.  Parallel with the filter output, reverse biased
C.  Series with the filter output, forward biased
D.  Series with the filter output, reverse biased

Ans:B

[9] A current surge takes place when a power supply is first turned on because
A.  The transformer core is suddenly magnetized
B.  The diodes suddenly start to conduct
C.  The filter capacitor must be initially charged
D.  Arching takes place in the power switch

Ans: C

[10] A dc electromagnet
A. Has constant polarity
B. Requires an air core
C. Cannot be used to permanently magnetize anything
D. Does not attract or repel permanent magnet

Ans: A

[11] In a multi-stage RC coupled amplifier the coupling capacitor______________

A) Limits the low frequency response

B) Limits the high frequency response

C) Does not affect the frequency response

D) Block the DC component without affecting the frequency response 

Ans: A

[12] It is required to measure temperature in the range of 13000 deg C to 15000 deg c. The most suitable thermocouple to be used as a transducer would be?

a) Chromel - constantan
b) Iron - constantan
c) Chromel - alumel
d) Platinum- rhodium

Ans: D

[13] Telemetering is a method of?
a) Counting pulses sent over long distances
b) Transmitting pictures from one place to another
c) Transmitting information concerning a process over a distance
d) None

Ans: C

[14] A dc to dc converter having an efficiency of 80% is delivering 16W to a load. If the converter is generating an output of 200V from an input source of 20V, then the current drawn from the source will be?
a) 0.1A
b) 0.5A
c) 1.0A
d) 10.0A

Ans: C

[15] The location of lighting arrestor is?
a) Near the transformer
b) Near the circuit breaker
c) Away from the transformer
d) None

Ans: D

Please leave your comments below...

Posted by admin 12:45 PM