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- ELectronic Measurement and Instrumentation - EMI
- 2016
- PYQ
**NIT ROURKELA - NITRKL**- Electronics and Communication Engineering
- B.Tech
**1 Views**- Uploaded 1 month ago

Roll No. :- Signature of Student:- Name:- Signature of Invigilator:- NATIONAL INSTITUTE OF TECHNOLOGY, ROURKELA-769008 MID-SEMESTER EXAMINATION, 2016 – 2017 (Spring) Subject Name: Electronic Instrumentation Subject Code: EC332 Dept. Code: EC No. of Pages: 3 Full Marks: 30 marks Duration: 2 hrs. Instruction to the candidates: i. ii. iii. iv. Give your name and roll no. and please get the signature of the invigilator above. The question paper consists of 8 questions (30 marks). Answer Q1 to Q3 in the question paper itself and attach to answer sheet. Answer all parts of the question together. Q1. a. Draw the waveform in Fig. 1, traced on the oscilloscope screen having dimensions 10 cm X 8 cm, if the input y signal applied to an oscilloscope is 4 sin(2π.106t) mV. The X plate sensitivity is 100 ns/cm, the delay in the Xdeflection circuitry is 100 ns and the delay in the Y-channel circuitry is 80 ns. The Y sensitivity is 1 mV/cm. Assume the trigger is set at 0 V and with a positive slope. Assume sawtooth generation along with blanking pulses are being generated and applied at the appropriate parts of the CRO. Indicate the important points on the screen (Fig.1). Show any calculations below in the empty space. Fig. 1 1|Page

b. Draw the waveform in Fig. 2, traced on the oscilloscope screen having dimensions 10 cm X 8 cm, if the input y signal applied to an oscilloscope is 4 sin(2π.106t + π/3) mV. and the trigger is set at 0 V but with a negative slope. Assume all other parameters set are same as in part-(a). Indicate the important points on the screen (Fig.2). Show any calculations below in the empty space. (4+2 = 6 marks) Fig. 2 Q2. Mention the number of significant figures Signficant Figures a. 3.05 mA b. 0.00305 Ω Q3. Signficant Figures c. 340 µV d. 305.000 kPa Round of the following values to 4 significant figures. Rounded Answer a. 4.0761 A b. 4.7550 V c. 4.4501 kΩ 2|Page (2 marks) (3 marks) Rounded Answer d. 123456 µV e. 34.9651 A f. 311111 pF

Q4. A resistor is measured eleven times and the following readings 200.2, 220.0, 200.0, 199.4, 200.0, 200.2, 200.2, 200.6, 199.6, 199.8 and 200.0 are obtained in Ω. Find the best value, average deviation, RMS deviation, standard deviation of the resistor and its probable error. Assume that systematic error is absent and that the distribution is normal. (5 marks) Q5. Legendre’s principle of least square states that the most probable value of any observed quantity is such that the sum of the square of deviations of the observations from the value is the least. Using this principle, show that the most probable value of a measured quantity is the mean of the observations. (3 marks) Q6. A resistor R has a difference of 25 V across its terminals when passing a current of 63.0 mA. The voltage is measured on a 30 V analog instrument with ± 5 % accuracy. The current is measured on a digital instrument with a ± 0.3 % Reading ± 1 digit accuracy. Calculate the resistance of R and specify its accuracy. (3 marks) Q7. The following are the measured values of currents and voltages in the circuit shown in Fig. 3. I1 = 1.11 A, I2 = 1.42 A, V1 = 10.9 V, V2 = 14.8 V. R0 is measured separately and is found to be 2.9 Ω. Find R1 and R2 to the correct number of significant figures. (4 marks) Fig. 3 Q8. A cathode ray tube (CRT) has an accelerating anode voltage VA applied to it. Assume that the vertical deflection plates of length ‘l’ are separated by a distance ‘d’ and ‘L’ is the distance between centre of deflection plate to screen. Derive an expression for the deflection sensitivity of the CRT mentioned above. If the parameters L = 0.5 m, VA = 40 kV and d = 4 cm and the l = 4 cm, determine the deflection sensitivity of the CRT. (3+1 =4 marks) 3|Page

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