** **

**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. The desired characteristics of a strain gauge are that it should have _________ and __________.

**(A)**
a resistance which is as low as possible, it should not have hysteresis effects
in its response.

**(B)** A resistance which is as high as possible, it should have
hysteresis effects is its response.

**
(C) **a
resistance which is as high as possible, it should not have hysteresis effects
in its response.

**(D)
**a resistance which is as low as practicable, it should have hysteresis
effects in its response.

b.

Considering the differential bridge amplifier shown in
Fig.1, if

_{},
_{} and _{}, then, _{} will be nearly
equal to ______ times the applied voltage E.

**(A)
**0.05.

**(B)
**0.0625.

**(C)
**0.005.

**(D)
**0.0125.

c. The aperture time of the sample-and-hold circuit is __________

**(A)
**the
time required for the switch to change state and the uncertainty in the time
that this change of state occurs.

**(B) **The length of time that the
circuit can hold the charge without dropping more than a specified percentage
of the initial value.

**(C) **The time taken by the
capacitor to charge upto half the value of the input voltage without any
leakage.

**(D) **The time taken by the
capacitor to charge upto the value of the input voltage.

d. Fixed standards which are kept for use in industrial laboratories are called _____________.

**(A)
** International
standards. **(B)** Secondary standards.

**(C)** Primary standards. **(D)**
Working standards.

e. If in a Wien
bridge circuit the measured frequency is 330 Hz and the resistors are each
equal to 53.6_{},
then each of the capacitors will be nearly equal to __________ _{}.

**(A)
**0.007.
**(B) **0.009.

**(C) **0.011 **(D)**
0.102.

f. If the
temperature coefficient of resistance of copper is 0.0045 and its resistance at
a temperature of _{}C
is 279.4 _{} then
its resistance at _{}C will be _______{}.

**(A)** 310 **(B)
**210

**(C) **260 **(D)**
220

g. In the decoder circuit of Fig.2, an
input of A = 0 and B = 1 will yield an output of __________.

**(A) **1101

**(B) **1011

**(C) **1110

**(D) **1010

h. The degree of refinement with which a measured value is stated is called _____________

**(A)
**Resolution **(B)
**Stability

**(C) **Precision **(D)**
Uncertainty

** **

i. One of the following equipment is not a passive transducer

**(A)** potentiometer element **(B)
**piezo resistive element

**(C) **Thermistor **(D)**
photovoltaic cells

j. A _{}-digit meter has a
resolution of _{}th
of the range and displays a maximum of __________.

**(A) **1099 **(B)**
1999

**(C)** 1000 **(D)
**2000

**Answer any FIVE Questions out of EIGHT
Questions. **

**Each question carries 16 marks.**

**Q.2** a. What
is meant by word ‘Calibration’? Explain how and where it is done. **(6)**

** **

b. Give
the classification of ‘Standards’. Describe in detail the setting up of any
two of them. **(10)**

** **

**Q.3** A
bridge is balanced at 1000 Hz and has the following constants: AB, _{} pure capacitance;
BC, 1000 _{} pure
resistance; CD unknown; DA, R = 600 _{} in parallel with C = 0.05 _{}. The terminals A
and C are connected to the a.c. supply. Find the R and C (or L) constants of
the arm CD, assuming that it is a series circuit. **(16)**

**Q.4** a. Explain
the terms (i) attenuator and (ii) probe as applied to a CRO. Give the circuit
of an active probe and describe its features. **(8)**

** **b. Given the following data,
compute the deflection sensitivity of a CRO:

** **Distance from the centre of
the deflection plates to the screen (L) 0.8m.

Effective
length of the deflection plates _{} 0.05m.

Distance between the deflection plates (d) 0.02m.

Accelerating
voltage _{} 1250V.

**(8)**

**Q.5** a. Distinguish
between the pairs

(i) Primary sensors and transducers.

(ii)
Active and Passive transducers. **(6)**

** **b. A resistance gauge with an unknown gauge factor is fastened to
a steel member subjected to a stress of 1120 kg/cm^{2}. The modulus of
elasticity of steel is _{} kg/cm^{2 }. If the
resistance of the unstrained gauge is 150 ohms and the change in resistance
_{} is 0.3 _{}, calculate the
gauge factor. **(10)**

** **

** Q.6 **Write notes on **any TWO **of the following:

(i) Different types of errors for time and frequency measurement.

(ii) Obtaining hysteresis loop under a.c. operating conditions.

(iii)
Digital voltmeter. **(8+8)**

** **

**Q.7** a. A
small AF voltage of 22 is superimposed on the RF test power and balance
achieved. If the RF test power is now turned off, an AF voltage of 34 is
required to balance the bridge. If the bridge arm has a resistance of 125 _{}, calculate the RF
test power. **(7)**

** **

** **b. In respect of radio
receiver measurements, describe any THREE of the following:

** **FM receiver alignment, sweep
alignment, non swept alignment, dual-sweep alignment. **(9)**

** **

**Q.8** a. Explain
the functions of the following parts of a spectrum analyser:

** **(i) attenuator (ii)
first IF filter

(iii)
local oscillator (iv) sweep voltage generator **(8)**

** **

b. Show
the basic elements of a function generator by means of a block diagram.
Explain the purpose of a constant current source, multivibrator and
resistance-diode shaping circuit in the same. **(8)**

** **

**Q.9** a. Explain
the terms:

(iv) aperture error and

(v)
quantization
error occurring in an A/D converter. **(4)**

** **

** **b. For the D/A converter
shown in Fig.4, compute the voltage

(i)
with only _{} closed and

(ii)

with only

_{} closed. **(12)**