Code: D-11               Subject: ELECTRONIC INSTRUMENTATION & MEASUREMENTS

Time: 3 Hours                                                                                                     Max. Marks: 100

NOTE: There are 9 Questions in all.

· Question 1 is compulsory and carries 20 marks. Answer to Q. 1. must be written in the space provided for it in the answer book supplied and nowhere else.

· Out of the remaining EIGHT Questions answer any FIVE Questions. Each question carries 16 marks.

· Any required data not explicitly given, may be suitably assumed and stated.

Q.1       Choose the correct or best alternative in the following:                                         (2x10)

a. A set of readings has wide range and therefore it has:

(A)  Low precision                              (B)  High precision

(C)   Low accuracy                              (D)  High accuracy

b. Thermocouple instruments can be used for a frequency range:

(A) up to 100 Hz                                (B)  up to 5000 Hz

(C)  up to 1 Hz                                    (D)  50 MHz and above

             c.   Electrostatic type instruments are primarily used as :

(A) Ammeter                                      (B)  Watt meter

(C)  Voltmeter                                     (D)  Ohmmeter

             d.   Frequency can be measured by using:

(A)  Maxwell’s bridge                        (B)  Schering’s bridge

(C)  Hay’s bridge                                (D)  Wien’s bridge

             e.   An aquadag is used in a CRO to collect:

(A) Primary electrons                         (B)  Secondary emission electrons

(C)  Both primary and secondary         (D)  None of the above

                            emission electrons

             f.    The Q factor of a coil at the resonant frequency of an RLC series circuit is 150.  The bandwidth is :

(A) 225 MHz                                     (B)  1.06 MHz

(C)  10 KHz                                        (D)  None of the aove

             g.   Piezo electric transducers are:

(A) Passive transducers                      (B)  Active transducers.

(C)  Inverse transducers.                      (D)  (B) and (C).

             h.   If a transducer has an output impedance of  and a load resistance of , it behaves as :

(A) a constant current source              (B) a constant voltage source

(C) a constant impedance.                   (D) none of the above

             i.    For a radio receiver, its sensitivity indicates:

(A) a response which is spurious        

(B)  the ability to reject an unwanted signed

(C) the measure of noise produced      

(D) the receiver’s ability to pick up weak signal

             j.    An 8 bit converter is used for a d.c. range of 0-10 V.  Find the weight of LSB 

(A)  39 mV                                         (B)  78 mV

(C)  39.2 mV                                      (D) None of the above

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

Q.2     a.   Explain the following terms

(i)   Accuracy                                      (ii)   Precision

                   (iii) Hysterisis                                       (iv)  Dead band                                       (8)

             b.   What are different types of errors in measurement?  Explain each briefly.             (8)

Q.3     a.   State the advantages and disadvantages of thermoelectric instruments.                 (8)

             b.   Explain how Wien’s bridge can be used for experimental determination of frequency.  Derive the expression for frequency in terms of bridge parameters.                                                                       (8)

Q.4     a.   What is a function generator?  Explain its working with the help of a block diagram.            (8)

b.   Discuss different types of oscilloscope probes.                                                    (8)

Q.5     a.   Describe principle of working of digital oscilloscope using a block diagram.                        (8)

b.   A Lissajous pattern on an oscilloscope is stationary and has 5 horizontal tangencies and two vertical tangencies.  The frequency of horizontal input is 1000Hz.  Determine the frequency of the vertical input.                                                           (8)

  Q.6     a. Explain the principle of period and time interval measurement.                             (8)

             b.   Describe reciprocating or period measurement method used in low frequency measurement.                                                                      (8)

Q.7     a.   Explain measurement of Flux Density by induced EMF.                                      (8)

b.   Explain how power can be measured at high frequency using the Bolometer method.                       (8)

Q.8     a.   Explain the following terms used for Arm receivers:

(i) Sensitivity.

(ii) Selectivity.

(iii) Dynamic range.

(iv) Noise range.                                                                              (8)

             b.   Describe the principle of working of a Hall Effect transducer.  Give its applications.             (8)

Q.9     a.   Draw the block diagram of a Data Acquisition system and explain its working.                   (8)

b.   Explain analog and digital multiplexing used in data acquisition systems.               (8)