Andhra University 2007 B.E Electronics & Communication Engineering - exam paper

II Year B.E./B.Tech Degree exam

ELECTRONIC MEASUREMENTS AND INSTRUMENTS

Electronics & Communication Engineering

Time : 3 hours Maximum : 75 Marks

ques. one is compulsory

ans any 4 from ques. two to 8

All ques. carry equal marks

1. a) describe Accuracy and Precision. (3M)

b) elaborate the 3 general classes of errors? (3M)

c) elaborate frequency standards? (3M)

d) What is a lissajous trend and its significance? (3M)

e) State the applications of a Spectrum analyzer. (3M)

2. a) provide the importance of Statistical analysis in measurements and discuss various kinds of statistical methods. (5M)

b) discuss Probability of errors and limiting errors (5M)

c) A set of independent current measurements was taken by
six observers and recorded as 12.8 mA, 12.2 mA, 12.5mA,

13.1 mA, 12.9 mA, 12.4 mA. compute Arithmetic Mean and avg. deviation. (5M)

3. a) discuss the principle of Suspension Galvanometer. (3M)

b) define Torque and deflection of the Galvanometer.(6M)

b) discuss shunt kind DC Ammeter. (6M)

4. a) discuss the frequency monitors for AM wave with neat
sketch (7M)

b) Derive the expression for frequency in terms of Wein Bridge
parameters. (8M)

5. a) Briefly discuss the working principle of Wheatstone Bridge.(7M)

b) discuss Shearing Bridge and derive the necessary expressions. (8M)

6. a) discuss the Maxwell’s Bridge and derive the expressions.(8M)

b) The ac bridge is in balance with the subsequent constants. Arm AB; R=450 W , arm BC; R=300W in series with C=0.265m F, arm CD unknown; arm DA; R=200W in series with L=15.9mH. The oscillator frequency is one KHz.
obtain the constants of arm CD. (7M)

7. discuss the phase and time interval measurements using oscillorgaphic representation of wave shape. (15M)

8. Write short notes on

a) Shunt kind ohmmeter (5M)

b) Cavity wave meter (5M)

c) Spectrum analyses (5M)

Earning:   Approval pending.