West Bengal Institute of Technology (WBIT) 2010-3rd Sem B.Tech Electronics and Communications Engineering WBUT,B-TECH,ESTER,ELECTRONIC MEASUREMENT AND INSTRUMENTATION(EMI)- - exam paper

ELECTRONICS MEASUREMENT AND INSTRUMENTATION 2010-11
GROUP--A
(Multiple option Questions)
1. select the accurate options for any ten of the following: 10 × one =10
i) Thermocouple transducer is used for
a) Temperature measurement
b)Velocity and vibration measurement
c) Pressure measurement
d) Acceleration measurement.
ii) The LVDT usually has 2 secondaries in
a) series addition b) series opposition
c) parallel addition d) parallel opposition
iii) Systematic errors are
a) Instrumental errors b) Environmental errors
c) Random errors c) both (A) and (B)
iv) Which of the subsequent bridges is preffered for the measurement of inductance
having high Q-factor
a) Maxwell's bridge b) Hay bridge
c) Owen bridge d) De Sauty bridge.
v) A digital voltmeter measures
a) peak value b) peak to peak value
c) rms value d) avg. value
vi) The guage factor is described as
a) (?L/L) / (?R/R) b) (?R/R) / (?L/L) c) (?R/R) / (?D/D) d) (?R/R) / (??/?).
vii) Creeping is observed in
a) watt-hourmeter b) wattmeter c) ammeter d) voltmeter
viii) A spectrum analyzer displays
a) various frequency amplitudes w.r.t. time b) peak-peak amplitude of modulating signal c)different signal amplitudes w.r.t. frequency d) Lissajous figures
ix) The resolution of a three & (1/2) digit DVM having a basic range of two volts is
a) 2V b) 1mV c) 0.25 V d) 0.125 V
x) A megger is used to measure
a) voltage b) current c) insulation resistance d) none of these
xi) Frequency can be measured by
a) Maxwell's bridge b) Wein's bridge c) Campbell bridge d) Schering bridge
xii) The principle of operation of Q-meter is based on
a) self-induction b) mutual induction c) series induction d) parallel resonance

GROUP—B (Short ans kind Questions) ans any 3 of the following: Marks:3 × 5=15
2. a) State the working principle of PMMC instrument b) define the method of damping used in this instrument. 2+3
3. a) What is Strain guage?
b) Derive an epression of guage factor a resistance wire strain guage. 1+4
4. discuss how Wein's bridge can be used for measurement of unknown frequencies. Derive an expression for frequency in terms of bridge parameters. 3+2
5. A moving coil instrument has the subsequent data:
Number of turns=100 Width of coil = 20mm, Depth of coil = 30 mm, Flux density in the air gap = 0.1 Wb/m2. Calculate the deflecting Torque when carrying a current of 10 mA. Also compute the deflection if the control spring constant is two × 10-6 N-m/degrees. 5
6. What is piezoelectric effect ? Mention identical applications of it. Name a few piezoelectric materials. two +1 +2
7. a) What is the fuction of spectrum analyzer? b) What is the purpose of function generator. Draw the blosk diagram of function generator. one + one +3
GROUP—C (Long ans kind Questions) ans any 3 of the following: 3×15=45
8. a) describe Point Accuracy.
b) define the available techniques of linearity with suitable diagram.
c) A set of independent 10 measurements were made to determine the weight of a lead shot. The weights in gm. Were as follows:
1.570, 1.597, 1.591, 1.562, 1.577, 1.580, 1.564, 1.586, 1.550, 1.5751.
` Determine the arithmetic mean, avg. deviation, standard deviation, variance, probable fault of 1 studying and probable eror of the mean. 2 + 5+ 8
9. a) discuss the functional block diagram of the CRO with a neat diagram.
b) What is Lissagous figures ? discuss how phase and frequency can be measured using these figures.
c) elaborate the differences ranging from CRO dual beam and dual trace ? What is the fuction of delay line? 7 + (1+3) + (3+1)
10. a) Draw and discuss the different blocks of Digital Multimeter.
b) A 3.5 digit multimeter has an accuracy of ± 0.5% studying ± 0.5 counts. If the meter reads 2mA on a full scale of 20mA,what is the worst case fault in reading?
c) With the help of functional block diagram,explain the working principle of swept TRF spectrum analyzer. 6 + three + 6
11. a) elaborate the types of errors that can occur while measuring low resistance using Wheatstone's bridge. ?
b)State why FETs are used in differential amplifier kind of electronic voltmeter.
c)Explain why compensating coil is used in Electrodynamometer wattmeter ?
d) discuss how range extension can be achieved in moving coil instruments. three + three + five +4
12. Describe how unknown capacitors can be measured using De-sauty's bridge. elaborate the limitations of this bridge and how can they be overcome by using a replaced De- sauty's bridge? Draw the revelant phasor diagrams. 7 +8
13. Write short notes on any 3 of the following: 3×5=15
a)Q-meter. B)SignalGenerator c)DC–potentiometer d)Dual slope ADC
e)Thermistors f)Wattmeter.

Earning:   Approval pending.