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# Multiple choice question for engineering

## Set 1

1. Resistive transducers are ______________
a) Primary transducers
b) Secondary transducers
c) Either primary or secondary
d) None of the mentioned

Answer: c [Reason:] Resistive transducers may be primary or secondary transducers according to application.

2. What will happen to resistance, if length of conductor is increased?
a) Decreases
b) No change
c) Increases
d) Doubles

Answer: c [Reason:] As length of conductor increases, resistance increases according to expression R = (ϱl)/A.

3. Which of the following can be measured using change in resistivity?
a) Temperature
c) Moisture content
d) All of the mentioned

Answer: d [Reason:] Change in resistivity can be brought in measurement of all the mentioned quantities, as resistivity is sensitive to temperature.

4. What will happen for resistivity metal and semiconductor if temperature is increased?
a) Increases
b) Decreases
c) For metal increases and for semiconductor decreases
d) For metal decreases and for semiconductor increases

Answer: c [Reason:] Metal has a positive temperature coefficient of resistance and semiconductor has a negative temperature coefficient of resistance.

5. What is the relation of temperature coefficient of resistivity on coefficient of thermal expansion in RTD?
a) Higher
b) Lower
c) Equal
d) None of the mentioned

Answer: a [Reason:] It is used to provide a considerable change in resistance when exposed to temperature.

6. A metal with temperature coefficient of resistance has a value 200, its initial resistance is given by 40Ω. For an increase in 300c to350c what will be the final resistance value?
a) 40 KΩ
b) 4 KΩ
c) 40 Ω
d) 400 Ω

Answer: a [Reason:] Answer obtained using expression RT=R0(1+αΔT), where α represents temperature coefficient of resistance, R0 and RT represents initial and final resistance values.

7. Which of the following can be used to measure using thermistors?
a) Very low
b) In-between 100Ω and 1MΩ
c) Greater than 1MΩ
d) None of the mentioned

Answer: b [Reason:] Thermistor at 200c can be used to measure resistance values in between 100Ω and 1MΩ.

8. Thermistors may be in wire form.
a) True
b) False

Answer: b [Reason:] Due to high brittleness thermistors cannot be form into wire type. Hence they are shaped into bead form.

9. Which of the following is correct for thermistors?
a) Positive temperature coefficient of resistance
b) Negative temperature coefficient of resistance
c) Unpredictable temperature coefficient
d) None of the mentioned

Answer: b [Reason:] For thermistors as temperature increase, resistance decreases.

10. Thermistors have high stability.
a) True
b) False

Answer: b [Reason:] Stability of thermistors are not satisfactory. They can be improved by using high temperature.

## Set 2

1. Seismic transducers are used to measure______________
a) Displacement
b) Velocity
c) Acceleration
d) All of the mentioned

Answer: d [Reason:] Seismic transducers can be used to measure small displacement like vibrations, velocity and acceleration.

2. Seismic mass has freedom to move any direction.
a) True
b) False

Answer: b [Reason:] Movement of seismic mass is limited to one direction using spring and damper system.

3. Relative displacement between housing frame and seismic mass in seismic transducer will be ____________
a) Xi(t)-Xm(t)
b) Xi(t)+Xm(t)
c) 2Xi(t)
d) 2Xm(t)

Answer: a [Reason:] Relative displacement between housing frame and seismic mass is the difference between absolute displacement of platform and displacement of mass.

4. Which of the following represents application of spring?
a) To provide stability
b) To provide oscillatory motion
c) To provide restoring force
d) None of the mentioned

Answer: c [Reason:] Spring is used to provide restoring force to mass when device displaces.

5. Damper system is used to ______________
a) Produce oscillations
b) Limit oscillations
c) To produce displacement
d) For indication

Answer: b [Reason:] Damper systems are used to limit oscillations made by mass when the device is displaced.

6. Which of the following represents correct relation for undamped natural frequency of system?
a) KM
b) (KM)1/2
c) K/M
d) (K/M)1/2

Answer: d [Reason:] Undamped natural frequency of a seismic transducer is the square root of ratio of restoring force and mass.

7. Seismic transducer is only applicable for displacement measurement.
a) True
b) False

Answer: b [Reason:] Seismic transducers can be used to measure both displacement, velocity and acceleration with several changes on the mass-spring-damper system.

8. Which of the following spring-mass arrangement is used for displacement measurement?
a) Soft spring small mass
b) Soft spring large mass
c) Stiff spring small mass
d) Stiff spring large mass

Answer: b [Reason:] For displacement measurement, Soft spring large mass arrangement is used. Only in this arrangement observable changes in position of mass can be detected.

9. How bandwidth can be increased?
a) Lowering natural frequency
b) Increasing natural frequency
c) Doubling natural frequency
d) Bandwidth cannot be increased

Answer: a [Reason:] Natural frequency can be lowered for increasing bandwidth of seismic displacement transducer. Which means spring must be softer and mass should be large.

10. Seismic displacement transducers are not suitable for measuring ______________
a) Vibrating velocities
b) Static velocities
c) Dynamic velocities
d) None of the mentioned

Answer: a [Reason:] In amplitude response for zero and infinite frequencies amplitude becomes zero and we don’t get any flat amplitude response.

## Set 3

1. Which of the following represents Laplace transform of ramp signal?
a) 1S3
b) 1S2
c) 1S
d) 1

Answer: b [Reason:] Ramp function is given as r (t) = t for all t >0. Its Laplace transform gives 1S2. Laplace transform can be found by: ∫0r(t)e-stdt.

2.
What does this function represents?
a) u (t)
b) u (t-2)
c) u (t+2)
d) u (-t)

Answer: b [Reason:] Given diagram represents a step function, which is shifted to right by two units and can write as u(t-2).

3. Laplace transform function f (t) is F(S), then how will you represent Laplace transform for differential of f (t)?
a) SF(S)
b) F(S)
c) S.F(S)
d) F’(S)

Answer: c [Reason:] This is obtained by time differential property of Laplace transform.

4. How will you obtain given function from unit step signals?
f (t) = 1 for -1≤t≤1
0 otherwise
a) u (t) – u (t+2)
b) u (t+1) – u (t-1)
c) u (t+1) + u(t-1)
d) 2.u (t)

Answer: b [Reason:] Given expression cancels common region in two functions, and the remaining will be function of our interest. u(t+1) is step signal with one unit left shifted, and u(t-1) is step signal with one unit right shifted.

5. How will you represent given function?

a) u (t)
b) eat.u(t)
c) e-at.u(t)
d) eat.r(t)

Answer: c [Reason:] Given function is a decreasing exponential with initial amplitude one, where u(t) represents step function. u(t) gives initial amplitude and negative power of exponential gives a negative slop to function.

6. Which of the following function is represented using given condition?
f (t) = 1 for t=0
0 otherwise
a) Step function
b) Sine function
c) Ramp function
d) Impulse function

Answer: d [Reason:] Impulse signal has a value only at t=0 and has zero value otherwise. Unit impulse function will have amplitude one at time t=0.

7. What is the result of the expression f(t)= u (t+2) – u (t-3)?
a) f (t) =1 for -2 ≤ t ≤ 3
b) f (t) =1 for 2 ≤ t ≤ 3
c) f (t) =1 for -2 ≤ t ≤ -1
d) f (t) =1 for -2 ≤ t ≤ 0

Answer: a [Reason:] u (t) is step function, and subtracting two shifted step functions will cancel their common region and produces new function. u(t+2) is a step signal with two units shifted left side and u(t-3) is a step signal with three units shifted right side.

8. Transfer function of a system is given by 1/S. If system has a step input, what will be the output in time domain?(Function exist only for positive time value)
a) Step signal
b) Impulse signal
c) Sinusoidal signal
d) Ramp signal

Answer: d [Reason:] Transfer function is ratio of Output to Input and hence Output can be obtained as a product of transfer function and input, which gives 1/S2. For a positive sided signal using inverse Laplace transform, output is obtained as ramp signal.

9. Function f (t) has Laplace transform F(S). How will you represent Laplace transform of integral of f(t)?
a) S.F(S)
b) F(S)
c) F(S2)
d) F(S)S

Answer: d [Reason:] This is obtained by integration property of Laplace transform.

10. Which of the following represents Laplace transform of sinh(at)?
a) a(S2+a2)
b) a(S2-a2)
c) S(S2+a2)
d) S(S2-a2)

Answer: b [Reason:] Given function represents hyperbolic sine function. Hyperbolic sine function can be represented as sinhx= (ex-e-x)2. Applying Laplace transform equation to this expression, we obtain Laplace transform of hyperbolic sine function.

## Set 4

1. Which of the given statement is true for zero-order system?
a) Varying transfer function with time
b) Constant transfer function
c) Transfer function= 1/S
d) Transfer function= 1/s2

Answer: b [Reason:] Order of a system is the maximum power of ‘S’ in characteristic equation. For a zero-order system, S will have a power zero and Transfer function will be a constant value.

2. Which of the given factor determines order of a system?
a) Maximum power of ‘S’ in characteristic equation
b) Minimum power of ‘S’ in characteristic equation
c) Value of constant value
d) None of the mentioned

Answer: a [Reason:] Maximum power of ‘S’ in characteristic equation is known as order of that system. For a zero-order system, power of ‘S’ will be zero and for first-order system maximum power of ‘S’ will be one.

3. Transfer function of a system is given by G(S) =b0 ⁄ a1S+a0 . What will be the static sensitivity of system?
a) b0 ⁄ a0
b) b0 ⁄ a1
c) a0 ⁄ b0
d) a1 ⁄ b0

Answer: a [Reason:] Transfer function can be converted into G(S) =K ⁄ (τS+1) , in which K is known as static sesistivity of system. Thus K can be expressed as a ratio of b0 and a0.

4. What will be the time constant for a system represented by transfer function G(S) =5/(3S+2)?
a) 3
b) 2.5
c) 1.5
d) 2

Answer: c [Reason:] Transfer function can be represented as G(S) =K/(τS+1) , in which time τ represents time constant. Time constant=3/2.

5. What will be the damping ratio of a system with transfer function G(S) =5/(3S2+2S+3) ?
a) 1.5
b) 0.5
c) 0.33
d) 2

Answer: c [Reason:] Damping ratio of a system with transfer function G(S) =b0 ⁄ (a2S2+a1S+a0 ) , can be found using equation a1 ⁄ (2√ a0a2) . Damping ratio of given system will obtain as 0.333 .

6. Which of the following represent condition for an over-damped system?
a) Damping ratio<0
b) Damping ratio=0
c) Damping ratio=0.5
d) Damping ratio>1

Answer: d [Reason:] A system with damping ratio ξ greater than 1 is said to be over damped system.

7. Which of the following represents a system with transfer function G(S) =5/(3S2+8S+3) ?
a) Over damped system
b) Un-damped system
c) Under damped system
d) None of the mentioned

Answer: a [Reason:] Damping ratio of a second order system can be found using equation a1/(2√a0a2 ) which is equal to 1.33. For a damping ratio greater than 1, system will be over damped system.

8. For a ramp input in second order system, which of the following represents correct relationship between natural frequency and steady state error?
a) Both are directly proportional
b) Both are inversely proportional
c) Both are equal
d) None of the mentioned

Answer: b [Reason:] Steady state error for second order system with ramp input can be represented as 2ξK/ωn , where ωn represents natural frequency.

9. What will be the static sensitivity of a system with transfer function G(S) =4/(5S2+8S+2) ?
a) 0.5
b) 2
c) 4
d) 4/5

Answer: b [Reason:] Static sensitivity of a system with transfer function G(S) =b0/(a2S2+a1S+a0 ) can be represented as b0/a0 .

10. Transfer function of a system with input y(t) =t2/2 is given by1/S. What will be the obtained output?
a) 6t3
b) t3/6
c) t3
d) t4

Answer: b [Reason:] Transfer function of a system is the ratio of output and input of the system in S domain. Output (in S domain)= Transfer function × Input (in S domain). Output in time domain can be obtained by finding inverse Laplace transform.

## Set 5

1. Output of a bimetallic element will be __________________
a) Strain
b) Pressure
c) Displacement
d) Voltage

Answer: c [Reason:] Bimetallic element is used for measuring temperature, it produces proportional output displacement for input temperature.

2. Which of the following can be used for measuring temperature?
a) Metallic diaphragm
b) Fluid expansion system
c) Capsule
d) Bourdon tube

Answer: b [Reason:] Fluid expansion system is a method for measuring temperature, in which expansion of liquid is measured with temperature.

3. IPTS stands for ________________
a) International Practical Temperature Scale
b) Indian Primary Temperature Scale
c) International Primary Temperature Scale
d) International Practical Temperature Standard

Answer: a [Reason:] IPTS is the short form of name International Standard Temperature Scale.

4. In liquid in steel bulb thermometer, which liquid can be used for measuring temperature up to 60000C?
a) Mercury
b) Ether
c) Water
d) None of the mentioned

Answer: a [Reason:] Mercury as a liquid provides temperature range of -4000C to 65000C.

5. Which of the following is used as indication instrument in liquid expansion system?
a) Bellows
b) Bourdon tube
c) Ammeter
d) Thermometer

Answer: b [Reason:] Bourdon tube converts pressure into displacement and in liquid expansion systems output expansion pressure is applied to bourdon tube for indication.

6. Which of the following is true for bimetallic type thermometer?
a) Two metals have same temperature coefficients
b) Two metals have different temperature coefficient
c) One metal is cooled always
d) None of the mentioned

Answer: b [Reason:] In a bimetallic type thermometer, two metals are used which are different in temperature coefficients.

7. When bimetallic thermometer heated, curling occurs to the side of metal with least temperature coefficients.
a) True
b) False

Answer: a [Reason:] A bimetallic type thermometer, when heated curls to the side of metal with least temperature coefficient. Number of curls will be proportional to temperature applied.

8. Analogous quantities of heat flow and temperature in electrical are _____________ and _______________
a) Potential and current
b) Current and potential
c) Power and potential
d) Current and power

Answer: b [Reason:] Heat flow in thermal system is analogous to current flow in electrical, and temperature between two points is analogous to potential between two points in electrical.

9. Ratio of net amount of heat received and stored in the body for certain time interval is known as _________________
a) Temperature
b) Thermal coefficient
c) Thermal storage capacity
d) None of the mentioned