9294 + Mcqs in Electronics and Communication Engineering Page 148 McqOptions

7351.	Which instrument needs creep compensation?
A.	Dynamometer wattmeter
B.	Induction wattmeter
C.	Energy meter
D.	Both (b) and (c)
Answer» D. Both (b) and (c)

Discussion

7352.	Two voltmeters are each 0-300 V range. Their internal resistances are 10 k&ohm; and 20 k&ohm; They are connected is series and a voltage of 400 V is applied. Their readings respectively will be
A.	266.6 and 133.3 V
B.	133.3 and 266.6 V
C.	200 V each
D.	100 and 300 V
Answer» C. 200 V each

Discussion

7353.	A 300 V voltmeter has an accuracy of 2% of full scale deflection. When the reading is 222 V, the actual voltage
A.	lies between 217.56 and 226.44 V
B.	lies between 217.4 and 226.6 V
C.	lies between 216 and 228 V
D.	is exact 222 V
Answer» D. is exact 222 V

Discussion

7354.	In a Ballistic galvanometer
A.	inertia is small and damping is also small
B.	inertia is large and damping is critical
C.	inertia is large and damping is small
D.	both inertia and damping are large
Answer» D. both inertia and damping are large

Discussion

7355.	The most commonly used moving iron instruments are
A.	repulsion type
B.	attraction type
C.	a combination of attraction and repulsion type
D.	none of the above
Answer» B. attraction type

Discussion

7356.	Assertion (A): A thermocouple transducer is based on Seeback effect.Reason (R): In a thermocouple transducer used for temperature measurement, the cold junction is usually kept in ice bath.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true R is false
D.	A is false R is true
Answer» C. A is true R is false

Discussion

7357.	In an Anderson bridge the unknown inductance is measured in terms of
A.	known inductance and resistance
B.	known inductance
C.	known capacitance and resistance
D.	known capacitance
Answer» D. known capacitance

Discussion

7358.	A moving iron instrument can be used for
A.	dc only
B.	ac only
C.	both dc and ac
D.	dc and high frequency ac
Answer» D. dc and high frequency ac

Discussion

7359.	The dead zone in a pyrometer is 0.125% of span. The calibration is 400 C to 1000 C. What temperature change might occur before it is detected.
A.	0.125 C
B.	0.75 C
C.	0.4 C
D.	1 C
Answer» C. 0.4 C

Discussion

7360.	Four voltmeters have following specifications. If accuracy is main consideration which is the best?
A.	100 V, 2 mA
B.	100 V, 100 mA
C.	100 V, 1 mA
D.	100 V, 0.1 mA
Answer» E.

Discussion

7361.	A sinusoidal signal is measured by CRO. The scale is set at 4 mV/cm. If vertical distance between positive and negative peaks is 6 cm, the peak value of ac signal is
A.	6 mV
B.	12 mV
C.	24 mV
D.	3 mV
Answer» C. 24 mV

Discussion

7362.	To avoid creep in an energy meter
A.	two shading bands are put on shunt magnet
B.	two shading bands are put on series magnet
C.	two holes are cut in the disc on opposite sides of spindle
D.	the potential coil is made of very thin wire
Answer» D. the potential coil is made of very thin wire

Discussion

7363.	A moving coil meter has a shunt of 0.02 &ohm; resistance. If coil resistance is 1000 &ohm; and a potential difference of 500 mV is required across it to cause full scale deflection, the current through shunt is
A.	2.5 A
B.	25 A
C.	0.25 A
D.	0.025 A
Answer» C. 0.25 A

Discussion

7364.	The deflection of a DArsonval galvanometer is measured through a mirror and scale. The mirror is 1 m away from the light source. The mirror is mounted on, the moving system. If mirror rotates through 0.2 rad the displacement on the scale is
A.	0.2 m
B.	0.4 m
C.	0.1 m
D.	0.05 m
Answer» C. 0.1 m

Discussion

7365.	A wire strain gauge has a gauge factor of 2, resistance of 125 &ohm; and length 1 m. If length of wire changes by .005 m, change in resistance will be
A.	0.25 &ohm;
B.	0.5 &ohm;
C.	1.25 &ohm;
D.	2.5 &ohm;
Answer» D. 2.5 &ohm;

Discussion

7366.	Assertion (A): A semiconductor strain gauge is more accurate than a resistance strain gauge.Reason (R): The gauge factor of a semiconductor strain gauge is about 100 where as the gauge factor of a resistance strain gauge is only about 2.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true R is false
D.	A is false R is true
Answer» B. Both A and R are true but R is not correct explanation of A

Discussion

7367.	The resistance of a dc galvanometer is 20 &ohm;. A current of 10 mA causes full scale deflection. To convert it into 0-300 V voltmeter, we have to use a series resistance of
A.	30000 &ohm;
B.	29980 &ohm;
C.	6000 &ohm;
D.	15 &ohm;
Answer» C. 6000 &ohm;

Discussion

7368.	The percentage limiting error in an instrument reading 8.3 V and having guaranteed accuracy of 1% of the full scale reading and range of 0-150 V is
A.	1.81%
B.	0.181%
C.	18.1%
D.	0.0018%
Answer» D. 0.0018%

Discussion

7369.	Which of the following instruments has non-linear scale? Moving coil instrumentMoving iron instrumentElectrostatic instrumentRectifier instrument Select the answer as per following codes
A.	2 only
B.	2 and 3 only
C.	2, 3 and 1
D.	1, 2, 3 and 4
Answer» C. 2, 3 and 1

Discussion

7370.	A rectifier voltmeter using bridge rectifier and PMMC meter is calibrated to read rms value of sine wave. A triangular wave is applied to it and it reads 6.82 V. The rms value of triangular wave is
A.	about 6.82 V
B.	about 7.1 V
C.	about 6.5 V
D.	about 10 V
Answer» C. about 6.5 V

Discussion

7371.	A radiation thermometer is suitable for temperatures
A.	below 500 C
B.	below 100 C
C.	above 500 C
D.	above 1400 C
Answer» E.

Discussion

7372.	Assertion (A): Thermocouple instruments can be used for ac only. Reason (R): Thermocouple instrument has a non linear scale.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true R is false
D.	A is false R is true
Answer» E.

Discussion

7373.	A meter has a resistance of 1 &ohm; and full scale deflection current of 1 mA. To convert into an ammeter of 1 A range, the shunt resistance should be
A.	1000 &ohm;
B.	1 &ohm;
C.	0.01 &ohm;
D.	0.001 &ohm;
Answer» E.

Discussion

7374.	Two wattmeter method is suitable only for balanced loads.
A.	True
B.	False
Answer» C.

Discussion

7375.	The power input and output in a device are 3650 W and 3385 W with each reading in doubt by 10 W. The percentage uncertainty in losses is
A.	7.55%
B.	3.77%
C.	11.32%
D.	15.09%
Answer» B. 3.77%

Discussion

7376.	A meter coil has a resistance of 100 &ohm; and a full scale deflection current of 10 mA. To convert it into a voltmeter of 0-200 V range, the series resistance should be
A.	20 k&ohm;
B.	19.9 k&ohm;
C.	1.9 k&ohm;
D.	20.1 k&ohm;
Answer» C. 1.9 k&ohm;

Discussion

7377.	Which of these has poor overload capacity?
A.	PMMC instrument
B.	Hot wire instrument
C.	Dynamometer instrument
D.	Both (a) and (c)
Answer» C. Dynamometer instrument

Discussion

7378.	Which instrument is based on induction principle?
A.	Dynamometer wattmeter
B.	Induction wattmeter
C.	Energy meter
D.	Both (b) and (c)
Answer» E.

Discussion

7379.	Which of these has a magnetic brake?
A.	Thermocouple ammeter
B.	Energy meter
C.	Dynamometer wattmeter
D.	Frequency meter
Answer» C. Dynamometer wattmeter

Discussion

7380.	Two numbers are 131 5 and 629 3. The sum of the numbers with range of doubt is
A.	760 8
B.	760 2
C.	760 + 8
D.	760 - 8
Answer» B. 760 2

Discussion

7381.	Assertion (A): Schering bridge is a low voltage bridge.Reason (R): Schering bridge is very commonly used for measurement of capacitance.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true R is false
D.	A is false R is true
Answer» E.

Discussion

7382.	The D'Arsonval- movement can be converted into audio frequency ac ammeter by adding a
A.	thermocouple
B.	transducer
C.	chopper
D.	rectifier
Answer» E.

Discussion

7383.	The resistance of a 125 &ohm; strain gauge changes by 1 ohm for 4000 micro strain. The gauge factor is
A.	1.5
B.	2
C.	2.5
D.	3
Answer» C. 2.5

Discussion

7384.	In Fermi-Dirac statistics, the probability of electron occupation of an energy level equal to Fermi level is
A.	0
B.	0.25
C.	0.5
D.	1
Answer» D. 1

Discussion

7385.	The dielectric losses do not depend on frequency.
A.	True
B.	False
Answer» C.

Discussion

7386.	Assertion (A): Resistivity of a perfect single crystal of a metal goes to zero as T approaches zero.Reason (R): Scattering of electrons is due to deviations from perfect periodicity of lattice.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» C. A is true but R is false

Discussion

7387.	Assertion (A): Intrinsic resistivity of silicon is lower than that of germanium.Reason (R): Magnitude of free electron concentration in germanium is more than that of silicon.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» E.

Discussion

7388.	A parallel plate capacitor has area of plate equal to 1 m and distance between plates is also 1 m2. The lossy dielectric has a complex dielectric constant r = 'r - j "r. If the capacitor is represented by R and C is parallel, then
A.	<img src="/_files/images/electronics-and-communication-engineering/materials-and-components/70-1.png">
B.	<img src="/_files/images/electronics-and-communication-engineering/materials-and-components/70-2.png">
C.	<img src="/_files/images/electronics-and-communication-engineering/materials-and-components/70-3.png">
D.	<img src="/_files/images/electronics-and-communication-engineering/materials-and-components/70-4.png">
Answer» B. <img src="/_files/images/electronics-and-communication-engineering/materials-and-components/70-2.png">

Discussion

7389.	Tesla is a unit of
A.	flux
B.	field strength
C.	flux density
D.	MMF
Answer» D. MMF

Discussion

7390.	If the operating temperature increases by 10 C, the rate of deterioration of solid dielectric becomes
A.	double
B.	one and a half time
C.	3 times
D.	4 times
Answer» B. one and a half time

Discussion

7391.	At 0 K, silicon and germanium behave like monoatomic crystals.
A.	True
B.	False
Answer» C.

Discussion

7392.	Assertion (A): Acceptor extrinsic semiconductor has higher conductivity than intrinsic semiconductor.Reason (R): Addition of p-type impurity produces an allowable discrete energy level just above valence band.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» B. Both A and R are true but R is not correct explanation of A

Discussion

7393.	The colour code on a carbon resistor is brown-black-red-gold. The value of resistance is
A.	100 &ohm;
B.	1000 &ohm;
C.	1000 &ohm; 5%
D.	1000 &ohm; 10%
Answer» D. 1000 &ohm; 10%

Discussion

7394.	Hysteresis curve is associated with motion of domain walls.
A.	True
B.	False
Answer» B. False

Discussion

7395.	A leakage capacitor can be represented by a capacitance C and resistance R in parallel C.
A.	True
B.	False
Answer» B. False

Discussion

7396.	For magnetic shielding, we need a ferromagnetic material.
A.	True
B.	False
Answer» B. False

Discussion

7397.	Assertion (A): Electronic polarizability increases as atoms becomes larger.Reason (R): For rare gas, 0( r - 1) E = Nae, where N is number of atoms/m3 and ae is electronic polarizability of material.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» C. A is true but R is false

Discussion

7398.	In a metal, the valence electrons
A.	are not shared
B.	are shared only between neighbouring atoms
C.	are shared by all atoms
D.	either (b) or (c)
Answer» D. either (b) or (c)

Discussion

7399.	All magnetic materials exhibit the phenomenon of saturation.
A.	True
B.	False
Answer» B. False

Discussion

7400.	Electric dipole moment is expressed in debye unit.
A.	True
B.	False
Answer» B. False

Discussion

Explore topic-wise MCQs in Engineering.

Which instrument needs creep compensation?

Two voltmeters are each 0-300 V range. Their internal resistances are 10 k&amp;ohm; and 20 k&amp;ohm; They are connected is series and a voltage of 400 V is applied. Their readings respectively will be

A 300 V voltmeter has an accuracy of 2% of full scale deflection. When the reading is 222 V, the actual voltage

In a Ballistic galvanometer

The most commonly used moving iron instruments are

Assertion (A): A thermocouple transducer is based on Seeback effect.Reason (R): In a thermocouple transducer used for temperature measurement, the cold junction is usually kept in ice bath.

In an Anderson bridge the unknown inductance is measured in terms of

A moving iron instrument can be used for

The dead zone in a pyrometer is 0.125% of span. The calibration is 400 C to 1000 C. What temperature change might occur before it is detected.

Four voltmeters have following specifications. If accuracy is main consideration which is the best?

A sinusoidal signal is measured by CRO. The scale is set at 4 mV/cm. If vertical distance between positive and negative peaks is 6 cm, the peak value of ac signal is

To avoid creep in an energy meter

A moving coil meter has a shunt of 0.02 &amp;ohm; resistance. If coil resistance is 1000 &amp;ohm; and a potential difference of 500 mV is required across it to cause full scale deflection, the current through shunt is

The deflection of a DArsonval galvanometer is measured through a mirror and scale. The mirror is 1 m away from the light source. The mirror is mounted on, the moving system. If mirror rotates through 0.2 rad the displacement on the scale is

A wire strain gauge has a gauge factor of 2, resistance of 125 &amp;ohm; and length 1 m. If length of wire changes by .005 m, change in resistance will be

Assertion (A): A semiconductor strain gauge is more accurate than a resistance strain gauge.Reason (R): The gauge factor of a semiconductor strain gauge is about 100 where as the gauge factor of a resistance strain gauge is only about 2.

The resistance of a dc galvanometer is 20 &amp;ohm;. A current of 10 mA causes full scale deflection. To convert it into 0-300 V voltmeter, we have to use a series resistance of

The percentage limiting error in an instrument reading 8.3 V and having guaranteed accuracy of 1% of the full scale reading and range of 0-150 V is

Which of the following instruments has non-linear scale? Moving coil instrumentMoving iron instrumentElectrostatic instrumentRectifier instrument Select the answer as per following codes

A rectifier voltmeter using bridge rectifier and PMMC meter is calibrated to read rms value of sine wave. A triangular wave is applied to it and it reads 6.82 V. The rms value of triangular wave is

A radiation thermometer is suitable for temperatures

Assertion (A): Thermocouple instruments can be used for ac only. Reason (R): Thermocouple instrument has a non linear scale.

A meter has a resistance of 1 &amp;ohm; and full scale deflection current of 1 mA. To convert into an ammeter of 1 A range, the shunt resistance should be

Two wattmeter method is suitable only for balanced loads.

The power input and output in a device are 3650 W and 3385 W with each reading in doubt by 10 W. The percentage uncertainty in losses is

A meter coil has a resistance of 100 &amp;ohm; and a full scale deflection current of 10 mA. To convert it into a voltmeter of 0-200 V range, the series resistance should be

Which of these has poor overload capacity?

Which instrument is based on induction principle?

Which of these has a magnetic brake?

Two numbers are 131 5 and 629 3. The sum of the numbers with range of doubt is

Assertion (A): Schering bridge is a low voltage bridge.Reason (R): Schering bridge is very commonly used for measurement of capacitance.

The D'Arsonval- movement can be converted into audio frequency ac ammeter by adding a

The resistance of a 125 &amp;ohm; strain gauge changes by 1 ohm for 4000 micro strain. The gauge factor is

In Fermi-Dirac statistics, the probability of electron occupation of an energy level equal to Fermi level is

The dielectric losses do not depend on frequency.

Assertion (A): Resistivity of a perfect single crystal of a metal goes to zero as T approaches zero.Reason (R): Scattering of electrons is due to deviations from perfect periodicity of lattice.

Assertion (A): Intrinsic resistivity of silicon is lower than that of germanium.Reason (R): Magnitude of free electron concentration in germanium is more than that of silicon.

A parallel plate capacitor has area of plate equal to 1 m and distance between plates is also 1 m2. The lossy dielectric has a complex dielectric constant r = 'r - j "r. If the capacitor is represented by R and C is parallel, then

Tesla is a unit of

If the operating temperature increases by 10 C, the rate of deterioration of solid dielectric becomes

At 0 K, silicon and germanium behave like monoatomic crystals.

Assertion (A): Acceptor extrinsic semiconductor has higher conductivity than intrinsic semiconductor.Reason (R): Addition of p-type impurity produces an allowable discrete energy level just above valence band.

The colour code on a carbon resistor is brown-black-red-gold. The value of resistance is

Hysteresis curve is associated with motion of domain walls.

A leakage capacitor can be represented by a capacitance C and resistance R in parallel C.

For magnetic shielding, we need a ferromagnetic material.

Assertion (A): Electronic polarizability increases as atoms becomes larger.Reason (R): For rare gas, 0( r - 1) E = Nae, where N is number of atoms/m3 and ae is electronic polarizability of material.

In a metal, the valence electrons

All magnetic materials exhibit the phenomenon of saturation.

Electric dipole moment is expressed in debye unit.

Two voltmeters are each 0-300 V range. Their internal resistances are 10 k&ohm; and 20 k&ohm; They are connected is series and a voltage of 400 V is applied. Their readings respectively will be

A moving coil meter has a shunt of 0.02 &ohm; resistance. If coil resistance is 1000 &ohm; and a potential difference of 500 mV is required across it to cause full scale deflection, the current through shunt is

A wire strain gauge has a gauge factor of 2, resistance of 125 &ohm; and length 1 m. If length of wire changes by .005 m, change in resistance will be

The resistance of a dc galvanometer is 20 &ohm;. A current of 10 mA causes full scale deflection. To convert it into 0-300 V voltmeter, we have to use a series resistance of

A meter has a resistance of 1 &ohm; and full scale deflection current of 1 mA. To convert into an ammeter of 1 A range, the shunt resistance should be

A meter coil has a resistance of 100 &ohm; and a full scale deflection current of 10 mA. To convert it into a voltmeter of 0-200 V range, the series resistance should be

The resistance of a 125 &ohm; strain gauge changes by 1 ohm for 4000 micro strain. The gauge factor is