Engineering, 29.10.2020 17:00, hoolio4495

A strain gauge, diaphragm pressure transducer (accuracy: <0.1% reading) is subjected to a pres- sure differential of 10 kPa. If the output is meas- ured using a voltmeter having a resolution of 10 mV and accuracy of better than 0.1% of the reading, estimate the uncertainty in pressure at the design stage. How does this change at 100 and 1,000 kPa

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answered: mjakabeast24

the design stage uncertainty for pressure is (√[ 25 + 0.10⁻⁴ P² ]) / 10 kPa

the change in sensitivity is 0.01 mV/kPa

Explanation:

Given that;

Differential pressure in the transducer ΔP = 10 kPa

Accuracy in the reading of diaphragm pressure transducer, α < 0.1%.

Resolution of the voltmeter, Rv = 10 mV

Now we write the expression for the design stage uncertainty

Us = √[(Us)₁² + (Us)₂²] equ 1

nex we write the expression for design stage uncertainty for the voltmeter having resolution 10 mV .

(Us)₁² = ± 1/2Rv

we substitute the values

(Us)₁² = ± 1/2(10 mV) = ±5 mV

we write the expression for design stage uncertainty with respect to strain gauge.

(Us)₂ = aKtΔP

Kt is the strain gauge constant, Rs is the resolution for the voltmeter when accuracy in strain gauge is less than 0.1% .

Substitute the values.

(Us)₂ = (0.1%) (P mV / kPa) 10 kpa

= 0.01P mV

Here, P is a constant.

Substitute the values in equation 1

Us = √[(±5 mV)² + (0.01P mV)²]

= √[ 25 + 0.10⁻⁴ P² ]

Write the expression for the design stage uncertainty for pressure

Up = Us / ΔP

Substitute the values.

Up = (√[ 25 + 0.10⁻⁴ P² ]) / 10 kPa

therefore the design stage uncertainty for pressure is (√[ 25 + 0.10⁻⁴ P² ]) / 10 kPa

Write the value of the design stage uncertainty for pressure, ΔP is 100 kPa .

(Up)₁ = (√[ 25 + 0.10⁻⁴ P² ]) / 100 kPa

Write the value of the design stage uncertainty for pressure ΔP is 1000 kPa

(Up)₂ = (√[ 25 + 0.10⁻⁴ P² ]) / 1000 kPa

Write the expression for the sensitivity of the pressure transducer.

s = Rv / 1000 kPa

Substitute the values

s = 10 mV / 1000 kPa

= 0.01 mV/kPa

therefore the change in sensitivity is 0.01 mV/kPa

answered: Guest

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explanation:

answered: Guest

Infrared sensor is most used sensor in wireless technology where remote controlling functions and detection of surrounding objects/ obstacles are involved. this post will discuss about what is infrared sensor, its working principle, how it works, types, applications, advantages and disadvantages. what is infrared sensor

ir sensor is a simple electronic device which emits and detects ir radiation in order to find out certain objects/obstacles in its range. some of its features are heat and motion sensing.

ir sensors use infrared radiation of wavelength between 0.75 to 1000µm which falls between visible and microwave regions of electromagnetic spectrum. ir region is not visible to human eyes. infrared spectrum is categorized into three regions based on its wavelength i.e. near infrared, mid infrared, far infrared.

wavelength regions of infrared spectrum

near ir – 0.75µm to 3 µm
mid ir – 3 µm to 6 µm
far ir – > 6 µm
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fig. 1 – introduction to infrared sensor

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infrared sensors works on three fundamental physics laws:

planck’s radiation law: any object whose temperature is not equal to absolute zero (0 kelvin) emits radiation.
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the key elements of infrared detection system are:

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ir transmitter acts as source for ir radiation. according to plank’s radiation law, every object is a source of ir radiation at temp t above 0 kelvin. in most cases black body radiators, tungsten lamps, silicon carbide, infrared lasers, leds of infrared wavelength are used as sources.

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ir receiver

generally ir receivers are photo diode and photo transistors. they are capable of detecting infrared radiation. hence ir receiver is also called as ir detector. variety of receivers are available based on wavelength, voltage and package.

ir transmitter and receivers are selected with matching parameters. some of deciding specifications of receivers are photosensitivity or responsivity, noise equivalent power and detectivity.