Thursday, 29 January 2015

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

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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


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


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


[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


[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


[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


[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


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


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


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


[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


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


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


[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


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


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

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Friday, 2 January 2015

Objective Questions on Batteries with Answers

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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


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


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


[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 O
(b) An e.m.f. of 2V and an internal resistance of 0.5 O
(c) An e.m.f. of 2V and an internal resistance of 0.1 O
(d) An e.m.f. of 10V and an internal resistance of 0.1 O


[5] Which of the following statements is false?
(a) A Leclanch� 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.


[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


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


[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


[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


[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.


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


[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


[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
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Saturday, 27 December 2014

Measurements and Instrumentation Objective Questions with Answers: Part-9

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MEASUREMENTS AND INSTRUMENTATION OBJECTIVE QUESTIONS WITH ANSWERS
[1] A rectifier type instrument is connected to 100VDC and is operated in the DC measuring module reads
(a) 111V
(b) 90V
(c) 50V
(d) 100V


[2] A permanent magnet moving coil ammeter has a coil resistance of 99ohm and Full Scale Deflection(FSD) current of 0.1mA. Shunt resistance is 1 ohm. Current through the meter at 0.5 F.S.D is
(a) 0.007mA
(b) 0.05mA
(c) 0.023mA
(d) 0.1mA


[3] One single phase wattmeter operating on 230V and 5A for 5 hours makes 1940 revolutions. Meter constant in revolutions is 400. What is the power factor of the land?
(a) 1
(b) 0.84
(c) 0.73
(d) 0.65


[4] For power measurement of three phase circuit by two wattmeter method, when the value of power factor is less than 0.5 lagging
(a) one of the wattmeters will read zero
(b) both give the same readings
(c) one of the wattmeter connections will have to be reversed
(d) pressure coil of the wattmeter will become ineffective.


[5] When using ohmmeter, applied voltage is to be disconnected from the circuit because
(a) Voltage source will increase resistance
(b) Current will decrease resistance
(c) the ohmmeter has its own internal battery
(d) non of the above


[6] Which wave has the least form factor?
(a) Square wave
(b) Rectangular wave
(c) Sine wave
(d) Triangular wave


[7] With a sweep time 10ms across the screen the approx. horizontal sawtooth frequency will be
(a) 50Hz
(b) 100Hz
(c) 1kHz
(d) 500Hz


[8] A spring controlled indicating instrument has a deflection of 90deg for maximum current I. The corresponding deflection for a gravity controlled instrument is
(a) 90�
(b) 120�
(c) 30�
(d) 0�


[9] It is found that 10A current passes through a resistor of 10ohms. The resistor has 5% tolerance . The error in measurement of current can be as high as 5%. What is max error in measurement of power, calculated from measured value of I and the nominal value of resistor?
(a) 100 W
(b) 150W
(c)50W
(d) 200W


[10] A resistor of 10Kohms with 5% tolerance is connected in parallel with a 5Kohms resistor of 10% tolerance. What is the tolerance limit for the parallel network?
(a) 5%
(b) 6.67%
(c) 10%
(d) 8.33%


[11] The resistance offered to the passage of an in-varying current by a column of mercury at the temperature of melting ice of mass 14.4521 gms of uniform cross-sectional area and length 106.3cm is
(a) Standard ohm
(b) One international ohm
(c) One ohm according to SI units
(d) One ohm according to working standards
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Tuesday, 18 November 2014

Measurements Instruments Objective Questions with Answers: part-8

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Measurements and Instruments Objective Questions with Answers

[1] The most preferred material for the control spring is
(a) German silver
(b) Platinum silver
(c) Silicon bronze
(d) Phosphor bronze


[2] A moving coil instrument is used as an ohmmeter. The indicating scale of the meter will be
(a) Hyperbolic
(b) Logarithmic
(c) Linear
(d) Inverse linear


[3] For high accuracy the meter has
(a) Supporting mirror
(b) Hand drawn scale
(c) Printed scale
(d) Scale with sharp pointer


[4] Among the voltages to various electrodes in a CRT the voltage is the highest on
(a) Aquadag
(b) Focusing anode
(c) Deflection plates
(d) PD anode


[5] In a free running oscilloscope the horizontal deflection system is driven by a ........ waveform
(a) Step
(b) Impulse
(c) Ramp
(d) DC


[6] A Lissajous patterns are used to measure
(a) Voltage and frequency
(b) Frequency and Phase shift
(c)  Frequency and amplitude distortion
(d) Amplitude and flux


[7] The shunt used in milliammeter
(a) will extend the range and reduce the meter resistance
(b) will extend the range and increase the meter resistance
(c) will decrease the range and meter resistance
(d) will not affect the meter


[8] The electrostatic instruments can be used without serious loss of accuracy upto ......... frequency
(a) 100Hz
(b) 100kHz
(c) 1 MHz
(d) 10MHz


[9] In the case of PMMC rectifier type instruments, the deflecting torque is proportional to
(a) Average value of AC current
(b) RMS of AC
(c) Instantaneous value
(d) Peak value


[10] Inductance and capacitance in the electrostatic system of units has the dimensions of
(a) mass
(b) mass-time
(c) mass length/time
(d) length


[11] For the indicating instrument the preferred damping condition is
(a) Critically damped
(b) a damping coefficient of 0.8 to 1
(c) Overdamped
(d) Underdamped


[12] One international ohm is equal to
(a) 1.00049 absolute ohm
(b) 0.99951 absolute ohm
(c) 0.969 absolute ohm
(d) 1.049 absolute ohm



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Sunday, 19 October 2014

Measurements Instrumentation Objective Questions Answers: Part-7

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Measurements Instrumentation Objective Questions with Answers

[1] A mulliammeter can be used as
(a) Voltmeter and ammeter
(b) Wattmeter
(c) Ohmmeter
(d) Frequency meter


[2] Which instrument has identical calibration for ac as well as dc values?
(a) Hot wire type
(b) Moving coil type
(c) Induction type
(d) Moving iron type


[3] An instrument to be used for measurement and control should preferably have
(a) Dead zone and dead time
(b) Linear output and fast response
(c) Non-linear output
(d) A highly damped response


[4] The current coil of a wattmeter is connected to the CT of R-phase. The potential coil is connected across Y and B phases. The wattmeter measures
(a) Active power in R phase
(b) Active power of Y phase
(c) Reactive power of R phase
(d) Power proportional to 3 phase power if the load is balanced


[5] The problem of Electro-static coupling in a transformer is acute at
(a) Low frequencies
(b) Power frequencies
(c) High frequencies
(d) High load on the transformer


[6] Which meter is suitable for the measurement of 10mV at 50MHz?
(a) Moving iron voltmeter
(b) VTVM
(c) Moving coil voltmeter
(d) CRO


[7] It can be stated that
(a) CT operates at almost the same flux density as a PT
(b) CT operates with a higher flux density than PT
(c) CT operates with considerably lower flux density than a PT
(d) no generalisation can be made with regard to the flux densities in CT and PT


[8] The thermocouple instruments do not have
(a) High sensitivity
(b) Absence of frequency error
(c) Independence of ambient temperature
(d) High degree of measuring accuracy


[9] Some wire- wound resistors have bifilar winding. This type of winding is used to
(a) Increase the thermal stability
(b) Reduce the tolerance
(c) Reduce the inductance of winding
(d) Double the power rating of the resistor


[10] Wien bridge is useful for measuring
(a) Very high frequency
(b) Low frequency
(c) Medium frequency
(d) High frequency


[11] A megger is usually
(a) Moving iron type instrument
(b) Electro-static type instrument
(c) Hot-wire type instrument
(d) Moving coil type instrument


[12] A moving iron ammeter may be compensated for frequency errors by
(a) a shunt resistance
(b) a series inductance
(c) shunt capacitance
(d) series resistance


[13] Ryall crest voltmeter is used for measurement of
(a) AC voltage of any form
(b) Low frequency voltage
(c) High DC voltage
(d) High AC voltage


[14] Jewels are used in instruments for the purpose of
(a) Damping
(b) Torque control
(c) Suppressing noise
(d) Bearing


[15] The thermocouple instrument will measure
(a) Current
(b) Voltage
(c) Flux
(d) None of the above
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Wednesday, 1 October 2014

Basic electronics Multiple Choice Questions: Part-6

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Basic electronics Multiple Choice Questions: Part-6

[1] A network designed to pass signals with all frequencies except those between two specified cut-off frequencies is called a
(a) low-pass filter
(b) high-pass filter
(c) band-pass filter
(d) band-stop filter


[2] A low-pass T-connected symmetrical filter section has an inductance of 200mH in each of its series arms and a capacitance of 0.5 �F in its shunt arm. The cut-off frequency of the filter is
(a) 1007 Hz
(b) 251.6 Hz
(c) 711.8 Hz
(d) 177.9 Hz


[3] A low-pass p-connected symmetrical filter section has an inductance of 200mH in its series arm and capacitances of 400 pF in each of its shunt arms. The cut-off frequency of the filter is
(a) 25.16 kHz
(b) 6.29 kHz
(c) 17.79 kHz
(d) 35.59 kHz


[4] A high-pass T-connected symmetrical filter section has capacitances of 400 nF in each of its series arms and an inductance of 200mH in its shunt arm. The cut-off frequency of the filter is
(a) 1592 Hz
(b) 1125 Hz
(c) 281 Hz
(d) 398 Hz


[5] A high-pass p-connected symmetrical filter section has a capacitance of 5000 pF in its series arm and inductances of 500 �H in each of its shunt arms. The cut-off frequency of the filter is
(a) 201.3 kHz
(b) 71.18 kHz
(c) 50.33 kHz
(d) 284.7 kHz


[6] A network designed to pass signals at frequencies above a specified cut-off frequency is called a
(a) low-pass filter
(b) high-pass filter
(c) band-pass filter
(d) band-stop filter


[7] A network designed to pass signals at frequencies below a specified cut-off frequency is called a
(a) low-pass filter
(b) high-pass filter
(c) band-pass filter
(d) band-stop filter


[8] A network designed to pass signals with frequencies between two specified cut-off frequencies is called a
(a) low-pass filter
(b) high-pass filter
(c) band-pass filter
(d) band-stop filter


The following refers to questions 9 and 10.
A filter section is to have a nominal impedance of 620 and a cut-off frequency of 2 MHz.

 [9] A low-pass T-connected symmetrical filter section is comprised of
(a) 98.68 �H in each series arm, 128.4 pF in shunt arm
(b) 49.34 �H in each series arm, 256.7 pF in shunt arm
(c) 98.68 �H in each series arm, 256.7 pF in shunt arm
(d) 49.34 �H in each series arm, 128.4 pF in shunt arm


[10] A low-pass p-connected symmetrical filter section is comprised of
(a) 98.68 �H in each series arm, 128.4 pF in shunt arm
(b) 49.34 �H in each series arm, 256.7 pF in shunt arm
(c) 98.68 �H in each series arm, 256.7 pF in shunt arm
(d) 49.34 �H in each series arm, 128.4 pF in shunt arm



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Wednesday, 27 August 2014

Measurements Instrumentation Objective Questions Answers: Part-6

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MCQ in Electrical Measurements and Instrumentation

[1] A 10MHz CRO has
(a) 5MHz sweep
(b) 10MHz vertical oscillator
(c) 10MHz horizontal oscillator
(d) 10MHz supply frequency


[2] Which of the following instruments can be used to measure AC current only?
(a) Permanent Magnet Type ammeter
(b) Induction type ammeter
(c) Moving iron voltmeter
(d) Moving iron ammeter
Answers:
1. D only
2. B only
3. A, B, D
4. B and D only


[3] An oscilloscope indicates
(a) Peak to peak value of voltage
(b) DC value of voltage
(c) RMS value
(d) Average value


[4] In a ballistic galvanometer, the deflecting torque is proportional to
(a) the current through coil
(b) square of current through coil
(c) square-root of current through coil
(d) sine of measured


[5] The error of an instrument is normally given as a percentage of
(a) measured value
(b) full-scale value
(c) mean value
(d) rms value


[6] If the instrument is to have a wide range, the instrument should have
(a) Linear scale
(b) Square-law scale
(c) Exponential scale
(d) Logarithmic scale


[7] The resistance can be measured most accurately by
(a) Voltmeter-ammeter method
(b) bridge method
(c) multimeter
(d) Megger


[8] The repeat accuracy of an instrument can be judged from its
(a) static error
(b) linearity error
(c) dynamic error
(d) standard deviation of error


[9] Which of the following meters has a linear scale?
(a) Thermocouple meter
(b) Moving iron meter
(c) Hot wore meter
(d) Moving coil meter


[10] No eddy current and hysteresis losses occur in
(a) Electrostatic instruments
(b) PMMC instruments
(c) Moving iron instruments
(d) Electrodynamo meter instruments


[11] Two voltmeters have the same range 0-400V. The internal impedance are 30,000 Ohms and 20,000 Ohms. If they are connected in series and 600V be applied across them, the readings are
(a) 360V and 240V
(b) 300V each
(c) 400V and 200V
(d) one of the meters out of the range and other 100V


[12] The full-scale deflection current of an ammeter is 1 mA and its internal resistance is 100Ohm. If this meter is to have full deflection at 5A, what is the value of the shunt resistance to be used?
(a) 49.99 Ohms
(b) 1/49.99 ohms
(c) 1 Ohm
(d) 2 Ohms


[13] The full-scale deflection current of an ammeter is 1 mA and its internal resistance is 100Ohm. This is to have full deflection when 100V is measured. What is the value of series resistor to be used?
(a) 99.99 K ohms
(b) 100 K ohms
(c) 99.99 ohms
(d) 100 ohms


[14] Why is a MISC meter not recommended for DC measurement?
(a) The meter is calibrated for AC and it's error for DC would be high
(b) The meter does not respond to DC signals
(c) The error is high due to hysteresis effect
(d) The error is high due to eddy current effect


[15] The EMF of Weston standard cell is measured using
(a) Moving- iron meter
(b) Moving-coil meter
(c) Digital Volt meter
(d) Potentiometer


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