Which of the following statements are correct ? A. Hygrometer measures the value of humidity directly B. Hygrometer measures the value of humidity indirectly C. Wien's bridge is used to measure the frequency of the signal D. Wien's bridge is used to measure the amplitude of the signal E. Bimetallic strip is a thermal expansion detector. Choose the most appropriate answer from the options given below :
A and C only
The five statements form two contradictory pairs plus one extra, so the task is to decide each pair and then match the options.
A vs B — how a hygrometer measures humidity. A hygrometer is the instrument dedicated to humidity, and it gives a direct reading of the moisture content of the air: a hair hygrometer responds to the length change of an organic fibre, while an electrical hygrometer responds to the change in resistance or capacitance of a hygroscopic film, and the scale is calibrated straight into % relative humidity. So A is TRUE and B is FALSE. (The genuinely indirect method is the psychrometer, which measures dry-bulb and wet-bulb temperatures and then infers humidity from psychrometric tables — that is the contrast the statement pair is testing.)
C vs D — what a Wien bridge measures. The Wien bridge balances only when both the resistive and the reactive conditions are met, and the second of these fixes the frequency:
\(f=\dfrac{1}{2\pi\sqrt{R_1R_2C_1C_2}} \quad \xrightarrow{\ R_1=R_2=R,\ C_1=C_2=C\ } \quad f=\dfrac{1}{2\pi RC}\)
The balance point therefore depends on the frequency of the applied signal, not on its amplitude, so the bridge is used as a frequency meter (and, with the same network in a positive-feedback loop, as the frequency-determining element of the Wien-bridge oscillator). C is TRUE and D is FALSE.
E — "Bimetallic strip is a thermal expansion detector." Physically this is sound: two metals of different expansion coefficients are bonded together, so a temperature rise bends the strip by an amount proportional to \((\alpha_1-\alpha_2)\Delta T\) — the principle of thermostats, thermal overload relays and dial thermometers. However, no option pairs E with both of the true statements, and the official key retains A and C as the answer.
Choosing the option. The only option containing both established truths (A and C) and nothing false is option 2.
Hence, the correct answer is A and C only.
Similar Questions
Which of the following statements are correct
A. Megnetostrictive transducer operation depends on the change of permeability of magnetic material is when strained.
B. Potentiometer is an active transducer.
C. Turbine flow meters are volumetric flow meters
D. Any metal can be thermistor.
E. Thermocouples are used in high accuracy measurements.
Choose the most appropriate answer from the options given below :
Match List I with List II
LIST I LIST II A. Stroboscope I. Changes its electrical resistance with temperature B. Bolometer II. Generate thermoelectric emf C. Thermocouple III. Changes pressure to displacement D. Diaphragm IV. For measurement of rotary motion Choose the correct answer from the options given below:
Match the following lists :
List – I List – II a. Electromechanical Device i. Seismic Device b. Optical Device ii. Piezo-electric c. Gyroscopic device iii. Interferometers d. Absolute motion device iv. Aerospace vehicle Choose the correct answer from the codes given below:
Consider the following transducers or transducer systems :
(a) Float elements
(b) Seismic system
(c) Gyroscope
Arrange the above transducers/systems in decreasing order of the availability of possible number of output signals.
Consider the following statements associated with electrical and electronic transducers
A. Little power is consumed by transducer
B. Mass intertia effects are not minimized
C. The response time is small
D. Transmission and processing the signal for the purpose of measurement are easier.
Choose the correct answer from the options given below:
Match List I with List II
LIST I LIST II A. Relative error I. The ability of tde device to give identical O/P when repeated measurements are made witd tde same I/P signal B. Precision II. The ratio of difference between measured value and tde true value to tde true value of tde measurand C. Caliberation III. The smallest increment in measure tdat can be detected witd certainity by tde instrument D. Resolution IV. The process of making adjustments or tde scale so tdat tde instrument reading conform to an accepted standard. Choose the correct answer from the options given below:
The fundamental law that is used in temperature measurement is known as
Assertion (A) : Normally, some standard signal conditioner and display devices are used with a transducer, unless they are custom-built to suit the requirements of the transducers.
Reason (R) : A transducer is a device which receives energy in one form and transfer it to a convenient form.
Select your answer using the codes given below :
Which of the following transducers are not linear ?
i. thermistor
ii. thermocouple
iii. IC sensorWhich of the following sensors has excellent linearity ?
Important Questions from Basics of Transducers
Which of the following can act as an inverse transducer?
For transducers, following statements are given:
(A) An optical interferometer is useful for measuring extremely small motions
(B) The damping ratio of a seismic instrument should be low for good dynamic performance
(C) A rate gyro is a relative motion measuring device
(D) A pneumatic motion transducer is non-linear over a wide range of motion
(E) A piezoelectric accelerometer can only be used for static motion measurement
Choose the correct answer from the options given below:
Choose the INCORRECT statement with respect to the use of electrical transducers.
Consider the following transducers:
1. LVDT
2. Piezoelectric
3. Thermocouple
4. Photovoltaic cell
5. Strain gauge
Which of these are active transducers?
Under which condition, Transducers must operate?
