IN Q.1-30 Carry One Mark Each. A zero error in a vernier caliper is termed as

Transcription

1 IN- Q Carry One Mark Each Q. A zero error in a vernier caliper is termed as accidental error systematic error interference error random error Q. Filtering is performed in surface finish measurement as a means of separating roughness and wavines. In roughness measurement, the wavelengths that are filtered out are half the cut-off wavelength shorter than the cut-off wavelength equal to the cut-off wavelength longer than the cut-off wavelength Q. 3 The following terms used in the context of an instrument are numbered as shown. () accuracy () sensitivity (3) precision and (4) resolution Match these with their possible definition listed below P. Repeatability of readings on successive observations Q. Smallest perceptible change in the output R. Deviation of the output from the true value S. Minimum value of the input from the true value T. Ratio of the change in the instrument reading to the change in measured variable - P, - Q,3 - R,4 - S - S, - Q,3 - P,4 - T - R, - T,3 - P,4 - Q - T, - Q,3 - P,4 - R Q. 4 For a proving ring used in a press, the value of force and its uncertainty are given as 355! 354 N without any rounding off. If the error should be rounded off at the maximum to two significant figures only, the value of the reading is rounded off as 300! 300 N 360! 350 N 400! 300 N 400! 400 N Q. 5 A viscous damper consists of a sliding piston and a cylinder filled with oil of kinematic viscosity 5 # 0-5 m /s. A damping force of 0 N is applied on the piston and the steady state velocity reached is 0 mm/s. The damping co-efficient of the damper is Ns/mm 4 Ns/mm 0 Ns/mm 0 Ns/mm

2 Q. 6 For a first order instrument a 5% settling time is equal to three times the time constant two times the time constant the time constant time required for the output signal to reaches 5% of the final value Q. 7 To avoid the effect of fringing, the potential of the guard ring of a capacitance transducer, shown in Fig. Q.7 is to be made equal to the ground potential half of the excitation voltage the voltage of the fixed plate the voltage of the moving plate Q. 8 The excitation frequency of an LVDT is khz. The maximum frequency of displacement should be limited to 00 Hz.5 khz khz.5 khz Q. 9 Assuming ideal diode characteristics, the input/output voltage relationship for the circuit shown in Fig. Q.9 is v0 (t) = vi (t), for all vi (t) v0 (t) = vi (t), for vi (t) > vr = 0, otherwise v0 (t) = vi (t), for vi (t), for vi (t) < vr = vr, otherwise v0 (t) = vi (t), for vi (t) > vr = vr, otherwise

3 Q. 0 The output of the opamp in the circuit of Fig. Q.0 is 0 V +.5 V Q. - 3 V + 3 V The device shown in Fig. Q. is a Variac Quadrac Triac Diac Q. The vectored address corresponding to the software interrupt command RST7 in 8085 microprocessor is 007H 007H 0038 H 0700H Q. 3 The number of comparators required in an 8-bit flash-type A/D converter is (8 + ) 8 Q. 4 The simplest form of the Boolean expression AB CD + AB CD + AB CD + ABCD is AD BC AB AB Q. 5 The two NAND gates before the latch circuit shown in Fig. Q.5 are used to act as buffers operate the latch faster avoid racing problem invert the latching action

4 Q. 6 Q. 7 Q. 8 If the Fourier transform of x [n] is X (e jw), then the Fourier transofrm of (- ) n x [n] is (- j) w X (e jw) (- ) w X (e jw) X (e j (w - p)) d [X (e jw)] dw The Nyquist rate of sampling of an analog signal s (t) for alias free reconstruction is 5000 samples/s. For a signal x (t) = [s (t)] the corresponding Nyquist sampling rate in samples/s is A signal x (t) = 5 cos (50pt - 60) is sampled at 00 Hz.The fundamental period of the sampled sequence x [n] is Q. 9 The brake magnet of an error free electromechanical, induction type energy meter is shifted from its position and moved a small distance towards the edge of the disc. Then the meter will continue to work correctly without any chage in its characteristics continue to work, but registers a lower kwhr continue to work, but registers a higher kwhr stop working Q. 0 A quartz peizo-electric type pressure sensor has a built in charge amplifier. The sensor has a sensistivity of mv/pa. It is subjected to a constant pressure of 0 kpa. The output of the transducer at steady state is 0 mv 00 mv 0 mv 0 mv Q. A dc voltage of magnitude kv is to be measured without loading the source under steady condition. the best-suited instrument is a rectifier type voltmeter an electrodynamic type voltmeter a megger an electrostatic voltmeter Q. In a single beam, single trace analog oscilloscope, a delay line is inserted between X-input and X-plates Y-input and Y-plates X-input and the trigger circuit Y-input and the trigger circuit Q. 3 The dominant poles of a servosystem are located at s = (-! j). The damping ratio of the system is

5 Q. 4 The steady state error due to a unit-step disturbance input D(s) in Fig. Q.4 is Q. 5 A thermocouple can be considered as a single capacity system with a time constant of 00 ms and unity gain. It is immersed in a heat bath whose temperature is varying at cc/s from 0cC. When the actual temperature of the heat bath is 70c C, the reading of the thermocouple will be 70.cC 7cC 69.9cC 69cC Q. 6 The proportional band of a PI controller is 50% and the reset time is 0. s. The transfer function of the controller is given by 50 b + l 50 b + l 0.s 5s b + l b + l s 5s Match the bipolar limb leads to the correct combination of electrodes used in ECG Group - Group - P. Lead I. Left leg and Right arm Q. Lead II. Left leg and Right leg R. Lead III 3. Left arm and Right arm 4. Left leg and Left arm P -,Q - 3,R - 4 P - 3,Q -,R - 4 P - 4, Q -, R - 3 P -, Q -, R - 4 Q. 7 Q. 8 The refractive index of the core of an optical fiber is n and that of the cladding is n. If (n - n) = 3 n, then fiber can be made single mode with numerical aperture unchanged by reducing core diameter and increasing 3 n reducting both core diameter and 3 n reducing core diameter alone reducing 3 n alone Q. 9 For nuclear radiation measurement, a proportional counter has, in comparison to a Geiger counter, lower dead time and higher count rate higher dead time and higher count rate higher internal amplification higher internal amplification and lower count rate

6 Q. 30 Water vapour absorbs electromagnetic radiation primarily in the range of X - ray IR UV g -ray Q.3-90 Carry Two Marks Each Q. 3 A device for measuring large internal diameters consists of two arms X and Y of length 50 mm each and pivoted at A (Fig. Q.3). These are fitted with 3 equal size rollers of diameter 0 mm. The arms are fitted with tilt sensors, which indicate the angle of inclination of the arms with reference to the axis of gravity measured in clockwise direction. If these angles of inclination of the arms X and Y are 90c and 40c respectively, then the internal diameter of the measured device is mm 8.6 mm 8.3 mm Q. 3 An outside micrometer having an anvil and spindle diameter of 6 mm is used for measuring the diameter of a cylindrical part having a nominal diameter of mm. During measurement, misalignment of the centerline of the work piece and measuring instrument has occurred. If the tilt of the shaft axis is 3c then the error in the measurement is,74 %.76%.3%.86% Q. 33 A cylindrical piece ground on a center-less grinding machine is uniformly three lobed. The contour of the lobed surface has the smaller radius r = 0 mm and the larger radius r = 0.3 mm. The size of a truly circular ring gauge, which just fits over this cylindrical pies, is 0.3 mm mm mm 0.5 Q. 34 The calibration data for a pressure compensator of a pump is given below Input x Output y For the given data, the slope of the best-fit line applying least square method is

7 Q. 35 A cantilever-type micro-accelerometer is desibned by scaling down each dimension of a macro-accelermeter by a factor of 00. If the natural frequency of the macroaccelerometer is w, then the natural frequency of the micro-accelerometer will be 00 w 0 w 0. w 0.0 w Q. 36 A pressure sensor has the following specifications Sensitivity at the design temperature = 0 V/MPa, Zero drift = 0.0 V/cC, Sensitivity drift = 0.0 (V/MPa)/cC When the sensor is used in an ambient 0 cc above the design temperature, the output from the device is 7.4 V. The true value of the pressure will be 0.7 MPa 0.68 MPa 0.65 MPa 0.6 MPa Q. 37 A variable capacitance angular velocity pickup is made with two concentrically mounted parallel semicircular plates with a small separation between them as shown in Fig. Q. 37. A dc voltage is connected across the terminals of the capacitance sensor as shown. For a constant angular velocity w, the waveform of the current i (t) will be dc triangular sinusoidal square Q. 38 A strain gauge of resistance 0 W and gauge factor.0 is at zero strain condition. A 00 kw fixed resistance is connected in parallel with it. Then the combination will represent an equivalent strain of mm/m zero mm/m mm/m Q. 39 An iron-constantan thermocouple is to be used to measure temperature between 0 and 300cC. With reference junction at 0cC, the emf induced at 00cC and 300 cc are E00 = 568m V, E300 = 635 mv Then the nonlinearity at 00cC as a percentage of full scale is + 3.3% -.06% % + 3.3% Q. 40 A quarts clock employs a ceramic crystal with a nominal resonance frequency of khz. The clock loose 30.3 s every 3 days. The actual resonance frequency of the crystal is khz khz khz khz

8 Q. 4 A single-sensor, contact-type ultrasonic flaw detector uses a frequency of 330 khz. When testing a specimen, an echo from a flaw is recorded 0.05 mass after the transmitted pulse. If the velocity of sound in the test object is 6.0 km/s then the flaw is at a depth of 0 cm 60 cm 30 cm 5 cm Q. 4 A PIN photo detector has a function capacitance of 6 pf, active area of 0 mm and a responsibility of 0.5 A/W. It is illuminated by a light of intensity mw/cm. A voltage output is obtained by connecting a 00 kw load resistor R in series L with the detector. The steady state voltage across RL will be 0.5 V.5 V 5.0 V 7.0 V Q. 43 An electromagnetic flowmeter is used to measure the average flow rate of a liquid in a pipe of diameter 50 mm. The flux density in the liquid has peak value of 0. T. The output from the flowmeter is taken to an amplifier of gain 000 and input impedance of MW. If the impedance of the liquid between the electrodes is 00 kw, then the peak value of the amplifier output voltage for an average flow velocity of 0 mm/s is.365 V V 0. V V Q. 44 The wiper of the 0 kw potentiometer in Fig Q.44 is positioned half way. Then the voltage V0 of the circuit is -.5 V V Q V +.5 V The parameters of the JEET in Fig. Q.45 are : gm = ma/v, rd = 5 kw. Neglecting the effect of the capacitor for A.C. analysis, the small signal A.C. voltage gain for the circuit is

9 Q. 46 The value of V0 in the circuit, shown in Fig. Q.46 is - 5 V + 3 V Q V + 5 V The gain ` v0 j of the amplifier circuit shown in Fig. Q.47 is vi 8 Q. 48 Q RL R The output voltage v0 in the circuit in Fig. Q.48 is R Vd R Vd R R R R V V R d R ( + d) V and V are the input voltage of an instrumentation amplifier. The output of the instrumentation amplifier is found to be 00 (V - V) (V + V). The gain and the common mode rejection ration (CMRR) of the instrumentation amplifier respectively are (50, 60 db) (50, 0 db) (00, 60 db) (00, 0 db)

10 Q. 50 The circuit in Fig. Q.50 is a and higher cut off w = H R C R C band-reject filter with lower cut-off w = and higher cut off R C wh = R C band-pass filter with lower cut-off w = and higher cut off wh = R C R C band-reject filter with lower cut-off w = and higher cut off R C wh = R C For the circuit shown in Fig. Q.5, the diode D is ideal. The power dissipated by the 300 W resistor is band-pass filter with lower cut-off w = Q W 0.75 W Q W.00 W Fig. Q.5 (a) shows a Schmitt trigger circuit and Fig. Q. 5 (b) the corresponding hysteresis characteristics. The values of VTL and VTH are VTL =- 3.75, VTH = V VTL = - V, VTH = + 5V VTL = - 5V, VTH = + V VTL = - 5V, VTH = + 5V

11 Q. 53 The sink current of the TTL NAND gate shown in Fig. Q.53 is 6 ma and the input capacitance of the CMOS NAND gate is 0 pf. The minimum pull-up time constant in ns for the CMOS gate with these specifications is Q. 54 In Fig. Q.54, if the input C = 0 and D = 0, the output Y can be made 0 by making Q. 55 A= A= A= A= 0,B 0,B,B,B = = = = 0 0 In Fig. Q.55, initially Q = A = B = 0. After three clock triggers, the states of Q,A and B will be respectively

12 Q. 56 In the digital circuit shown in Q.56, the fliflop have set time of 5 ns and a worst case delay of 5 ns. The AND gate has a delay of 5 ns. Maximum possible clock rate for the circuit to operate faithfully is MHz 5 MHz MHz 30 MHz Q. 57 7EH and 5FH are XORed. The output is multiplied by 0H. The result is 00H 7E5FH 5F7EH 00 H Q. 58 The following 8085 instructions are executed sequentially PROG: XRA A MOV L, A MOV H, L INX H DAD H After execution, the content of HL register pair is 0000H 00H 000H 000H Q. 59 In the circuit of Fig, Q. 59 A, B, C are the inputs and P, Q are the two outputs. The circuit is a half adder where P is the sum of Q is the carry half adder where P is the carry and Q is the sum full adder where P is the sum and Q is the carry full adder where P is the carry and Q is the sum

13 Q. 60 Q. 6 Q. 6 Vectors x = 5i - j + k and x = 4i - j + k are transformed into y = Ax and R VW S 3 3W S 3 W. S y = Ax using an orthogonal matrix A = 3 3W S 3 -W S S 3 3 3W X T The cosine of the angle between y and y is Due to an amplitude modulation by a sine wave, if the total current in the antenna increases from 4A to 4.8A the depth of modulation in percentage is , a and b < with the ROC Given X (z) = az - bz - specified as a < z < b, x 0 of the corresponding sequence is given by 3 Q A direct form implementation of an ITI system with H (z) = z + 0.3z - is shown in Fig. Q.63. The value of a0, a and a are respectively.0, 0.7 and , and 0.3 Q , 0.7 and.0 0.3, and.0 A low-pass filter has a sampling frequency ft = 0 khz. The passband (fp) and stop band (fs) edge frequencies are khz and 3 khz respectively. The frequency axis is pre-warped before applying bilinear transformation to get new angular frequencies, Wp and Ws. The ratio of the warped edge frequencies (Ws /Wp) is Q. 65 a. Assuming a s + a sampling time of T seconds, the poles of the transfer function H (z) for an equivalent digital system obtained using impulse in variance method are at (eat, e - at) ` j a, - j a j T T A casual, analog system has a transfer function H (s) = (e jat, e - jat ) (eat/, e - at/)

14 Q. 66 A discrete-time signal, x [n], suffered a distortion modeled by an LTI system with H (z) = ( - az - ), a is real and a >. The impulse response of a stable system that exactly compensates the magnitude of the distortion is ` jn u [n] -` jn u [- n - ] a a an u [n] an u [- n - ] Q. 67 A digital notch filter with a notch frequency of 60 Hz is to transformed into one operating at a new notch frequency of 0 Hz. The sampling frequency is 400 Hz. A lowpass-to-lowpass transformation z - = - az is used on the first to obtain z-a the new notch filter. The the value of a should be Q. 68 The resistance values of the bridge circuit shown in Fig. Q.68 are R = R = R3 = R and R4 = R + 3 R. The bridge is balanced by introducing a small voltage v. The value of 3 R is Rv E Rv E - v Q. 69 Rv E-v Rv E + v In the ac bridge shown in Fig. Q.69 the detector D reads zero. Then Z is made of 50 mh in parallel with 50 W 50 mh in series with 50 W 50 mh in series with 50 W 50 nf in parallel with 5 kw

15 Q. 70 A 3-phase balannced R-L load is connected to a 3-phase balanced symmetrical 400V, 50 Hz, RYB sequence mains as shown in Fig. A.70. The wattmeter W reads.73 kw. Then the active power in the load is.73 kw the reactive power of the load is.73 kvar the active power in the load is 3 kw the reactive power of the load is 3 kvar Q. 7 An unknown impedance Z is shunted across an ac current source of value cos (0t)A. The current source develops a voltage of s cos (0t + 45c) V. The value of the impedance is 3 W resistance in series with 0.3 H inductor 3 W resistance in parallel with 0.3 H inductor 3 W resistance in series with 0.3 F capacitor 3 W resistance in parallel with 0.3 F capacitor Q. 7 An ideal diode has been connected across a 0 W, 00 ma, center-zero PMMC meter as shown in Fig. Q.7. The meter will read + 00 ma ma ma ma Q. 73 A wire potentiometer of length m and resistance W/m balances a standard cell vaoltage of.08 V at a length of 0 m 8 cm. If the voltage of the battery supplying the current through the potentiometer is.0 V, then the value of the series resistance connected to the potentiometer is 9 W 90 W 900 W 990 W Q. 74 A Q-meter having an insertion resistance of 0.0 W is used to measure the inductance of a coil. Resonance occurs at an angular frequency of 06 rad/s with a capacitance of 40 pf. The inductance of the coil is 50 mh 05 mh 5 mh 0.5 H

16 Q. 75 A symmetrical square wave of frequency 5 khz and a peak-to-peak amplitude of 0 V is fed to Y-input of a single channel oscilloscope. The screen appears as shown in Fig. Q.75. Then the X and Y sensitivities and the trigger settings respectively are 5 ms/cm, V/cm and + ve slope 0 ms/cm, V/cm and +ve slope 5 ms/cm, V/cm and -ve slope 0 ms/cm, V/cm and -ve slope Q. 76 A certain system exhibited an overshoot of 6% when subjected to an input of u (t), where u (t) is a step input. The damping ratio and decay ratio respectively are (0.8, 0.080) (0.5, 0.056) (.0, 0.66) (., ) Q. 77 The torque-speed curve of a constant field armature controlled DC servomotor is shown in Fig. Q.77. The armature resistance in W and torque constant in Nm/A of the motor respectively are (.76, 0.68) (.00, 0.5) Q. 78 A certain closed loop system with unity feedback has the forward pth transfer K function given by G (s) =. With the gain set at the ultimate value, s (s + )( s + 5) the system will oscillate at an angular frequency of 5 rad/s 6 rad/s Q. 79 (.76, 0.85) (0.0, 0.8) rad/s 3 rad/s Fig. Q. 79 shows the Bode magnitude plot of a system. The minimum phase transfer function of the system is given by

17 Q ` s + j 0` s + j s` s + j s` s + j (s + ) 8 (s + ) s (s + 0) s (s + 0) Fig Q.80 shows the polar plot of a system. The transfer function of the system is 5( + 0.s) 5 ( + 0s) Q. 8 Q. 8 Q. 83 Q. 84 ( + 0.5s) 5 ( + s) - 0. s The loop transfer function of a system is given by G (s) = e. The phase s crossover frequency is given by p p 0 p p 0. 4 Consider the following systems: System : G (s) = (s + ) System : G (s) = (5s + ) The true statement regarding the system is Bandwidth of system is greater than the bandwidth of system Bandwidth of system is lower than the bandwidth of system Bandwidth of both the systems are the same Bandwidth of both the systems are infinite y (s) A state space representation for the transfer function is = s+6 u ( s ) s + 5s x = x = Ax + Bu, where A = =, B = ; E, - 6-5G and the value of C is ; E [6 ] = [ - 5] - 0G The transmittance of a particular solution measured is T. The concentration of the solution is now doubled. Assuming that Beer-Lambert s law holds good for both the cases, the transmittance of the second would be T T T T

18 Q. 85 In Fick s method of cardiac output measurement, oxygen consumption is 00 ml/ min., arterial oxygen constent is 0.30 ml/ml and venous oxygen content is 0.0 nl/ml. The cardiace output in /min. is Q. 86 A He-Ne laser of cavity length 500 mm has an oscillating bandwidth of 500 MHz. The maximum number of longitudinal oscillating modes that is accommodated within the bandwidth is Q. 87 A step index fiber has a core refractive index of.46 and a cladding refractive index of.45. The pulse dispersion in ns/km due to the effect of numerical aperture alone is Q. 88 The time taken by an ionized atom, of mass m kg and charge e Coulombs, pulsed into a field-free region with V volts, to reach a detector L meters away is m m L L ev ev m L ev L m ev Q. 89 In a Michelson s interferometer illuminated by a coherent and wuasi-monochromatic light source, a very small frequency shift is introduced in the light returning from one of the arms. The effect on the observed fringe pattern is a decrease in contrast an increases in contrast appearance of two sets of the same pattern uniform movement across the observation plane Q. 90 In an ideal X-Ray tube operated at 40 kv, the short wavelength limit of X-Ray emission in A is (Planck s constant h = 6.66 x 0-34 Js, Charge of an electron e =.6 # 0-9 coulomb, velocity of light C = 3 # 08 m/s

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