# RTU Previous Exam Papers BE EC 3rd Semester

# Electronic Measurements and Instrumentation Feb-2011

**Unit-I**

1. a) The following 10 observations were recorded when measuring a voltage :31.6, 31.0, 31.7,31.0, 32.1,31.9, 31.0, 31.9, 32.5 and 31.8 volt, find

i) the probable error of one reading.

ii) the probable error of mean.

b) Define the following for Gaussian distribution of data:

i) Precision index.

ii) Probable error

in) Standard deviation of mean

Standard deviation of Standard Deviation.

**OR**

a) A Circuit was tuned for resonance by eight different students and the values of resonant frequency in KHz were recorded as 432,447,444,435,446,444, 436 and 441. calculate

i) Standard deviation

ii) Variance.

b) Define the following with suitable examples.

i)Precision

ii)Accuracy m) Repeatability

i)Drift related to the instruments.

**Unit-II**

2. a) Explain the block diagram of D.C. voltmeter with Direct coupled Amplifier.

b) Explain the working principle of vector impedance meter with neat sketch.

**OR**

a) What do you mean by the term ‘Q-factorExplain the working of Q-meter.

b) Write short notes on RF power and voltage measurements.

**Unit-III**

3. a) Calculate the velocity of the electron beam in an oscilloscope if the voltage applied to its vertical deflection plates is 2200 V. Also calculate the cut off frequency if the maximum transit time is 114 of a cycle. The length of horizontal plates is 65 mm.

b) Explain the following terms of CRO:

i) Blanking circuit

ii) Astigmation Control.

**OR**

a) Explain the different types of sweeps used in a CRO.

b) Explain the following terms of CRO :

i) Z-axis modulation

ii) Sources of synchronization

**Unit-IV**

4. a) Explain the working of frequency synthesized signal generators with neat sketch.

b) Explain the block diagram of frequency selective wave analyser.

**OR**

a) Explain the Construction and working of Heterodyne wave analyser.

b) Explain the block diagram of spectrum analyzer and its applications.

** **

**Unit-V**

5. Write short notes on the following :

a) Seismic Accelerometers.

b) RVDT

**OR**

Write short notes on the following

a) Ultrasonic flow meters

b) Thermocouples.