Measurements and Instrumentation A. Voltmeter having a resistance of 5 kΩ
1. To increase Q factor of a coil, the wire should be B. Voltmeter having a sensitivity of 1 kW/V
A. long C. Voltmeter having sensitivity of 10 kW/V
B. thin 4. In 3 phase power measurement by two D. None of the above
wattmeter method, the reading of one wattmeter Resistance of voltmeter should be very high as
C. thick
is zero. The power factor of load is compared to 20 kΩ.
D. long and thin
A. 1 B. 0.5 C. 0 D. 0.8 8. A single phase energy meter has the rating 1200
Q is high if resistance is low. Therefore, wire resolutions/ kWh. If a 500 W electric gadget is used
When p.f. = 0.5, 0 = 60° and one of the wattmeters
should be thick. for 4 hours, the energy meter will make
reads zero.
2. An ammeter of 0-25 A range has a guaranteed A. 1200 revolutions
5. In a CRO which of the following is not a part of
accuracy of 1% of full scale reading. The current
electron gun B. 1800 revolutions
measured is 5 A. The limiting error is
A. cathode C. 2100 revolutions
A. 2% B. 2.5% C. 4% D. 5%
B. grid D. 2400 revolutions
C. accelerating anode 0.5 x 4 = 2 kWh = 2 x 1200 revolutions.
D. X - Y plates 9. Assertion (A): De sauty's bridge is suitable only
. Electron gun consists of cathode, grid and for pure capacitor.
accelerating anode. Reason (R): Capacitors are mostly perfect.
3. The coil of a moving iron instrument has a
resistance of 500 Ω and an inductance of 1 H. It 6. If reference sound pressure P0 is 2 x 10-5 A. Both A and R are true and R is correct
reads 250 V when a 250 V dc is applied. If series N/m^2, a sound pressure of 90 dB is equal to explanation of A
resistance is 2000 Ω, its reading when fed by 250 V, A. 0.632 N/m^2 B. Both A and R are true but R is not correct
50 Hz ac will be
B. 0.707 N/m^2 explanation of A
A. 260 V
C. 0.835 N/m^2 C. A is true R is false
B. 252 V
D. 0.925 N/m^2 D. A is false R is true
C. 250 V
Capacitors are mostly imperfect.
D. 248 V
. 10. In which of the transformer is the secondary
nearly short circuited under normal operating
7. Which of the following voltmeters would you
conditions?
use for measuring voltage across 20 kΩ resistance?
A. CT
,B. PT D. 600∠ - 150° Ω
.
C. Distribution transformer
D. Power transformer 14. Assertion (A): When a wattmeter is used for
low impedance loads, the pressure coil is
CT is operated with secondary short-circuited connected across the load.
otherwise a high emf would be induced across .
secondary. Reason (R): A wattmeter measures apparent
power. 17. In a ballistic galvanometer, a charge of 100 μC
11. A moving coil instrument has a resistance of gives a first swing of 25°. The charge required to
0.6 Ω and full scale deflection at 0.1 A. To convert it A. Both A and R are true and R is correct cause first swing of 50° is
into an ammeter of 0-15 A range, the resistance of explanation of A
shunt should be A. 200 μC
B. Both A and R are true but R is not correct
A. 0.6 Ω B. 0.06 Ω explanation of A B. 400 μC
C. 0.1 Ω D. 0.004 Ω C. A is true R is false C. 50 μC
D. A is false R is true D. 25 μC
. Wattmeter measures active power. swing is proportional to charge.
12. A piezoelectric force transducer has a charge 15. As per BIS there are 6 accuracy classes of 18. Two resistors R1 = 36 Ω ± 5% and R2 = 75 Ω ±
sensitivity of 20 pC/N. It is connected to a charge instruments. 5% are connected in series. The total resistance is
amplifier and overall gain of transducer and
amplifier is 50 mV/N. The gain of amplifier is A. True B. False A. 111 ± 0 Ω
There are 8 classes of accuracy as per BIS. B. 111 ± 2.778 Ω
A. 1 mV/pC B. 1.5 mV/pC
C. 2.5 mV/pC D. 4 mV/pC 16. In figure, Z1 = 200∠60° Ω, Z2 = 400∠ - 90° Ω, Z3 C. 111 ± 5.55 Ω
= 300∠0°. Then Z4 for bridge to be balanced is D. 111 ± 7.23 Ω
.
13. An LVDT is used to measure displacement. The
LVDT feeds a Voltmeter of 0-5 V range through a
250 gain amplifier. For a displacement 0.5 mm the Total maximum error ± (1.8 + 3.75) = ± 5.55 Ω.
output of LVDT is 2 mV. The sensitivity of
19. Figure shows an RC potentiometer to measure
instrument is
ac voltage. It is desired that V0/Vi should be
A. 0.1 V/mm B. 0.5 V/mm A. 150∠30° Ω independent of frequency. The value of C should
be
C. 1 V/mm D. 5 V/mm B. 400∠ - 90° Ω
Final output = 2 x 10-3 x 250 = 0.5 V. C. 300∠90° Ω
, D. 22 sin ωt + 45°) = 240 x 10-6 or I = 2 mA.
When signals to X and Y plates are in phase, the 25. Consider the following statements: In a
display is a straight line inclined at 45°. differential amplifier using JFET, the differential
22. The angle δ for a mica capacitor is about output offset is due to
A. 25° B. 15° C. 5° D. 1° 1.mismatch between FET parameters
Mica capacitor has very low loss and loss angle δ 2.difference in values of resistances used in circuit
is very very small. 3.variation in supply voltage.
A. 10 μF
23. A digital voltmeter has a read out range from 0 Of the statements, the correct statements are
B. 11 μF
to 999 counts. If the full scale reading is 9.999 V,
C. 0.1 μF the resolution is A. 1 and 2
D. 0.09 μF A. 1 V B. 1, 2, 3
Since resistances are in the ratio of 10 : 1, B. 0.01 V C. 2, 3
capacitances should be in the ratio of 1 : 10
C. 1 mV D. 1, 3
because XC ∝ 1/C.
D. 1 μV Variation in supply voltage affects both amplifiers
20. In a strain measuring device using a strain
equally.
gauge, the output quantity is Resolution is the smallest change in the quantity
being measured which will cause an observable 26. Magnetic flux density has the dimensions
A. voltage
change in output. In this case it is 1 mV.
A. MI^-1T^-2 B. M^-1I^-2T^-2
B. resistance
24. The coil of a moving coil meter has 100 turns,
C. ML^-3T^-2 D. MI^-1T^-3
C. impedance is 40 mm long and 30 mm wide. The control torque
is 240 x 10-6 N-m on full scale. If B = 1 Wb/m2, Flux density = flux/area.
D. either (a) or (b)
range of meter is
27. A meter with a resistance of 100 Ω and a full
The measurement is done using an unbalanced
A. 1 mA scale deflection of current of 1 mA is to be
bridge.
converted into voltmeter of 0 - 5 V range. The
B. 2 mA
21. The Lissajous pattern observed on screen of multiplier resistance should be
CRO is a straight line inclined at 45° to x axis. If X- C. 3 mA
A. 490 Ω B. 5000 Ω
plate input is 2 sin ωt, the Y-plate input is
D. 4 mA
C. 4900 Ω D. 5100 Ω
A. 2 sin ωt
NBAI = Controlling torque or
B. 2 sin (ωt + 45°)
.
C. 2 sin (ωt - 45°)
1. To increase Q factor of a coil, the wire should be B. Voltmeter having a sensitivity of 1 kW/V
A. long C. Voltmeter having sensitivity of 10 kW/V
B. thin 4. In 3 phase power measurement by two D. None of the above
wattmeter method, the reading of one wattmeter Resistance of voltmeter should be very high as
C. thick
is zero. The power factor of load is compared to 20 kΩ.
D. long and thin
A. 1 B. 0.5 C. 0 D. 0.8 8. A single phase energy meter has the rating 1200
Q is high if resistance is low. Therefore, wire resolutions/ kWh. If a 500 W electric gadget is used
When p.f. = 0.5, 0 = 60° and one of the wattmeters
should be thick. for 4 hours, the energy meter will make
reads zero.
2. An ammeter of 0-25 A range has a guaranteed A. 1200 revolutions
5. In a CRO which of the following is not a part of
accuracy of 1% of full scale reading. The current
electron gun B. 1800 revolutions
measured is 5 A. The limiting error is
A. cathode C. 2100 revolutions
A. 2% B. 2.5% C. 4% D. 5%
B. grid D. 2400 revolutions
C. accelerating anode 0.5 x 4 = 2 kWh = 2 x 1200 revolutions.
D. X - Y plates 9. Assertion (A): De sauty's bridge is suitable only
. Electron gun consists of cathode, grid and for pure capacitor.
accelerating anode. Reason (R): Capacitors are mostly perfect.
3. The coil of a moving iron instrument has a
resistance of 500 Ω and an inductance of 1 H. It 6. If reference sound pressure P0 is 2 x 10-5 A. Both A and R are true and R is correct
reads 250 V when a 250 V dc is applied. If series N/m^2, a sound pressure of 90 dB is equal to explanation of A
resistance is 2000 Ω, its reading when fed by 250 V, A. 0.632 N/m^2 B. Both A and R are true but R is not correct
50 Hz ac will be
B. 0.707 N/m^2 explanation of A
A. 260 V
C. 0.835 N/m^2 C. A is true R is false
B. 252 V
D. 0.925 N/m^2 D. A is false R is true
C. 250 V
Capacitors are mostly imperfect.
D. 248 V
. 10. In which of the transformer is the secondary
nearly short circuited under normal operating
7. Which of the following voltmeters would you
conditions?
use for measuring voltage across 20 kΩ resistance?
A. CT
,B. PT D. 600∠ - 150° Ω
.
C. Distribution transformer
D. Power transformer 14. Assertion (A): When a wattmeter is used for
low impedance loads, the pressure coil is
CT is operated with secondary short-circuited connected across the load.
otherwise a high emf would be induced across .
secondary. Reason (R): A wattmeter measures apparent
power. 17. In a ballistic galvanometer, a charge of 100 μC
11. A moving coil instrument has a resistance of gives a first swing of 25°. The charge required to
0.6 Ω and full scale deflection at 0.1 A. To convert it A. Both A and R are true and R is correct cause first swing of 50° is
into an ammeter of 0-15 A range, the resistance of explanation of A
shunt should be A. 200 μC
B. Both A and R are true but R is not correct
A. 0.6 Ω B. 0.06 Ω explanation of A B. 400 μC
C. 0.1 Ω D. 0.004 Ω C. A is true R is false C. 50 μC
D. A is false R is true D. 25 μC
. Wattmeter measures active power. swing is proportional to charge.
12. A piezoelectric force transducer has a charge 15. As per BIS there are 6 accuracy classes of 18. Two resistors R1 = 36 Ω ± 5% and R2 = 75 Ω ±
sensitivity of 20 pC/N. It is connected to a charge instruments. 5% are connected in series. The total resistance is
amplifier and overall gain of transducer and
amplifier is 50 mV/N. The gain of amplifier is A. True B. False A. 111 ± 0 Ω
There are 8 classes of accuracy as per BIS. B. 111 ± 2.778 Ω
A. 1 mV/pC B. 1.5 mV/pC
C. 2.5 mV/pC D. 4 mV/pC 16. In figure, Z1 = 200∠60° Ω, Z2 = 400∠ - 90° Ω, Z3 C. 111 ± 5.55 Ω
= 300∠0°. Then Z4 for bridge to be balanced is D. 111 ± 7.23 Ω
.
13. An LVDT is used to measure displacement. The
LVDT feeds a Voltmeter of 0-5 V range through a
250 gain amplifier. For a displacement 0.5 mm the Total maximum error ± (1.8 + 3.75) = ± 5.55 Ω.
output of LVDT is 2 mV. The sensitivity of
19. Figure shows an RC potentiometer to measure
instrument is
ac voltage. It is desired that V0/Vi should be
A. 0.1 V/mm B. 0.5 V/mm A. 150∠30° Ω independent of frequency. The value of C should
be
C. 1 V/mm D. 5 V/mm B. 400∠ - 90° Ω
Final output = 2 x 10-3 x 250 = 0.5 V. C. 300∠90° Ω
, D. 22 sin ωt + 45°) = 240 x 10-6 or I = 2 mA.
When signals to X and Y plates are in phase, the 25. Consider the following statements: In a
display is a straight line inclined at 45°. differential amplifier using JFET, the differential
22. The angle δ for a mica capacitor is about output offset is due to
A. 25° B. 15° C. 5° D. 1° 1.mismatch between FET parameters
Mica capacitor has very low loss and loss angle δ 2.difference in values of resistances used in circuit
is very very small. 3.variation in supply voltage.
A. 10 μF
23. A digital voltmeter has a read out range from 0 Of the statements, the correct statements are
B. 11 μF
to 999 counts. If the full scale reading is 9.999 V,
C. 0.1 μF the resolution is A. 1 and 2
D. 0.09 μF A. 1 V B. 1, 2, 3
Since resistances are in the ratio of 10 : 1, B. 0.01 V C. 2, 3
capacitances should be in the ratio of 1 : 10
C. 1 mV D. 1, 3
because XC ∝ 1/C.
D. 1 μV Variation in supply voltage affects both amplifiers
20. In a strain measuring device using a strain
equally.
gauge, the output quantity is Resolution is the smallest change in the quantity
being measured which will cause an observable 26. Magnetic flux density has the dimensions
A. voltage
change in output. In this case it is 1 mV.
A. MI^-1T^-2 B. M^-1I^-2T^-2
B. resistance
24. The coil of a moving coil meter has 100 turns,
C. ML^-3T^-2 D. MI^-1T^-3
C. impedance is 40 mm long and 30 mm wide. The control torque
is 240 x 10-6 N-m on full scale. If B = 1 Wb/m2, Flux density = flux/area.
D. either (a) or (b)
range of meter is
27. A meter with a resistance of 100 Ω and a full
The measurement is done using an unbalanced
A. 1 mA scale deflection of current of 1 mA is to be
bridge.
converted into voltmeter of 0 - 5 V range. The
B. 2 mA
21. The Lissajous pattern observed on screen of multiplier resistance should be
CRO is a straight line inclined at 45° to x axis. If X- C. 3 mA
A. 490 Ω B. 5000 Ω
plate input is 2 sin ωt, the Y-plate input is
D. 4 mA
C. 4900 Ω D. 5100 Ω
A. 2 sin ωt
NBAI = Controlling torque or
B. 2 sin (ωt + 45°)
.
C. 2 sin (ωt - 45°)
