Thermoelectric-thermometer There are two worlds in modern engineering. Piezometers are used to monitor pore water pressure and are sometimes referred to as pore pressure cells. The most used piezoelectric materials are PZT, a ceramic containing lead titanate and lead zirconate and PZLT, a ceramic of lead-lanthanum-zirconate-titanate. The rated capacities of strain-gauge load cells range from 1 N to more than 50 MN, and they can be used with high-resolution digital indicators as force transfer standards. For example photovoltaic cell in which light energy is converted into electrical energy. The turbine-governor characteristics corresponding to the generators are P 1 =50(50 − f), P 2 = 100(51 − f), P 3 = 150(52 − f) Where, f denotes the system frequency in Hz, and P 1, P 2, P 3 are the power outputs of the turbines in MW. Explanation:- 1. The tube is kept vertical and its other end is open to atmosphere. The following are the advantages of converting the physical quantity into an electrical signal. Explanation:- Acting as a secondary transducer, LVDT can be used as a device to measure force, weight & pressure etc. 2. Linearity: The output voltage of LVDT is almost linear for displacement up to 5mm. Load cells can measure tension, compression, or shear. Disadvantages of LVDT Which if the following moving particles cannot be deflected by magnetic fields ? The photoconductive materials most frequently used include cadmium sulfide (CdS) and cadmium selenide (CdSc). Also, to reduce the surface tension and capillarity effects. These devices are also called photoresistive cells or photoresistors since the change in conductivity appears as a change in resistance. δE = ±5mv ). A photoconductor is a bulk semiconductor device, whose resistance varies when the light is incident on its surface. High-temperature measurement:- Iron constantan or copper constants are used to measure temperate upto 300°C and thermocouples of nickel-iron are used to measure temperature opts 600°C. Wide bandwidth and high accuracy are required. Explanation:- Where Q98. Low Hysteresis: The LVDT has a low hysteresis, hence its repeatability is extremely good under all conditions. This type of manometer can only be used for measuring small and moderate pressures because as the pressure to be measured increases, the corresponding length of the piezometer tube required for measurement also increases. Resistance thermometers Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. When the length of the tube becomes longer, it cannot be handled conveniently. Which of the following transducers is most suitable for monitoring continuous variations in very fine thickness of a material ? Modify the input signal. The LVDT can be used in all applications where displacement ranging from fractions of a few mm to a few cms have to be measured. In which part of the scale does the pointer indicate most accurately? For measuring electric charges; As null – point detectors in ac bridges; As null – point detectors in dc bridges; For measuring power; Ans. They are sensitive to stray magnetic fields. at the pressure below its vapor pressure can be used to measure temperature down to 1 K. Ques.69. Shear is induced by tension or compression along offset axes. These include frequencies in the infrared, visible and ultraviolet radiations. For strain gauge devices, strain gauges (strain-sensitive variable resistors) are bonded to parts of the structure that deform when making the measurement. δE = ± 5% of 100 A transducer is a device that converts energy from one form to another. For piezoelectric devices, a piezoelectric material is compressed and generates a charge that is conditioned by a charge amplifier. is connected in. Same as a photovoltaic cell Sometimes the term solar cell is reserved for devices intended specifically to capture energy from sunlight, while the term photovoltaic cell is used when the light source is unspecified. 1. Assuming generators and transmission network to be lossless, the system frequency for a load of 700 … The range can be increased to 600°C by filling the space above mercury with some inert gas. The most used piezoelectric materials are PZT, a ceramic containing lead titanate and lead zirconate and PZLT, a ceramic of lead-lanthanum-zirconate-titanate. The dynamic response is limited. Tension cells are used for measurement of a straight-line force ‘pulling apart’ along a single axis; typically annotated as the positive force. There is two main type of pyrometer, namely the total radiation pyrometer and the optical pyrometer. Also, to reduce the surface tension and capillarity effects. MCQ in Electrical Circuit part 9 as part of the Electronics Engineering Board Exam. The response time of CdS units is about 100 ms and of CdSe cells is 10 ms. Show Explanation These strain gauges are typically used as elements in a Wheatstone bridge circuit, which is used to make the measurement. The main drawbacks of ultrasonic flow-meter are, Affected by pressure and temperature variations, Hydrometer is employed for determination of, Inductive method can be used for measuring thickness of, Both magnetic and non-magnetic materials, as well as non-conducting and conducting materials. Variable resistance: transducer is a strain gauge. These are inexpensive, tiny in size, and need an RPS (regulated power supply).The level of the mV signal is very low, and it is restricted to small distances like 200 feet. If voltage supply to the energy meter is more than the rated value, energy meter will run, Aluminium is selected as the material for rotating disc of energy meter because, For making shunts the material suitable is that which has, Negligible thermoelectric e.m.f. Variable inductance: transducer is a linear variable differential transformer, Variable capacitance: transducer is a parallel plate capacitor with a variable gap, Synchros and resolvers: used to measure angular displacement. Ruggedness: The LVDT is mechanically rugged and can withstand mechanical shock and vibrations. They derive the required power for energy change from an exterior power source. A high resistance is usually connected in series with an electrostatic voltmeter, Deflection of a hot wire instrument is proportional to, Instantaneous value of alternating current, Following type of instrument is used to measure very small currents of high frequency, Permanent magnet moving coil type ammeter. 1) The scale of the moving iron instruments is not uniform and is cramped at the lower end. However, this interference can be reduced by shielding. c) converts a non-electrical information signal into an electrical form. They produce an output signal in the form of some variation in resistance, capacitance or any other electrical parameter, which than has to be converted to an equivalent current or voltage signal. The various disadvantages of moving iron instruments are. These include frequencies in the infrared, visible and ultraviolet radiations. ANSWER: Potentiometer. 5) These are capable of giving good accuracy. Best for ITI and Diploma Students. A hot-wire anemometer is a device used to measure : The device used for measuring flow of air around an aeroplane is. The main electrical displacement transducers work on the principle of. The shape of the elastic element used in load cells depends on a number of factors, including the range of force to be measured, dimensional limits, final performance, and production costs. hA is the height of the liquid column in the piezometer tube. Depending upon the principle of transduction, they are further classified as: Electromagnetic Various types of load cells include hydraulic load cells, pneumatic load cells, and strain gauge load cells. The tube is kept vertical and its other end is open to atmosphere. Attraction type moving instrument. Low-temperature measurement: Thermocouples of Iron-constantan and copper constantan are used to measure temperature as low as 18 K and gold-platinum and silver platinum thermocouples are used to measure below 18 K with high accuracy. The electrical transducers used for continuous recording and control of humidity are, Measurements of flow, thermal conductivity and liquid level using thermistros make use of, In viscosity meters the quantity measured is, The function of the reference electrode in a pH meter is to, The method used for analysis of gases and their mixtures is called as, The disadvantage(s) of capacitor microphones is/are, The devices extensively used in sound measurement system are, A linear displacement digital transducer uses. Answer.4. Transducer - MCQs with answers Q1. All semiconductors can be considered as photoconductors. Strain gauge-based load cells have a sensing junction/element that when loaded responds to the load by producing an electrical output. 8) If a balloon ... of the two wattmeter used for the measurement of power input to a 3 phase induction motor are 850 W and 250 W respectively. The circuitry to convert the response to a quantifiable electrical signal is a configuration known as the Wheatstone bridge. ... You may also need. Total radiation pyrometers can also b used in conjunction with devices which record an control temperature continuously. The piezometer tube is a vertical glass tube inserted in the wall of a pipe or a vessel containing the liquid whose pressure is to be measured. Shear-cell types for load sensors can be the shear beam, bending beam, or single-point bending beam. This test is Rated positive by 87% students preparing for Electrical Engineering (EE).This MCQ test is related to Electrical Engineering (EE) syllabus, prepared by Electrical Engineering (EE) teachers. PA = whA Explanation:- Which one of the following pressure transducers is suitable for measurement of high pressure ? Multiple-Choice Questions. The height of the liquid in the tube above any point in the fluid indicates the pressure of the liquid at that point. Advantages of LVDT: High temperature: A mercury thermometer (boiling point of mercury is 357°C) can be used to measure temperature upto 300°C. Variable inductance: transducer is a linear variable differential transformer Increase with the speed of the hand driven dynamo, Decrease with the speed of the hand driven dynamo, Remain constant irrespective of the speed, Primary of an instrument transformer (C.T.) As we know that displacement is a vector quantity representing a change in position of a body or a point with respect to a reference. i.e., 1mm displacement of the care produces an output voltage of 300 mV. Generally, a transducer with an mV electrical output can be used in laboratory applications. c Damping material. 3) The increase in temperature increases the resistance of the coil, decreases the stiffness of the springs, decreases the permeability and hence affect the reading severely. PHOTOCONDUCTIVE CELLS Such substance is known as. Ea = 100 ± 5 Which of the following improves sound transmission from the transducer element into the tissue? The transduction medium may be resistive, inductive or capacitive depends on the conversion process that how input transducer converts the input signal into resistance, inductance and capacitancerespectively. One of the unique characteristics of the piezoelectric effect is that it is reversible, meaning that materials exhibiting the direct piezoelectric effect (the generation of electricity when stress is applied) also exhibit the converse piezoelectric effect (the generation of stress when an electric field is applied). All of the given option are correct, LINEAR VARIABLE DIFFERENTIAL TRANSFORMER (LVDT). Between 1000°C and 1600°C Platonism Rhodium thermocouple is used. Having response independent of variation in humidity, temperature and atmospheric pressure. Answer.4. Narrow bandwidth and low accuracy are required/sufficient. A strain gauge is a passive transducer … The actual value of limiting error can be expressed as A pinoybix mcq, quiz and reviewers. A lead thermometer may be used to measure temperature as low as -250°C and below these temperature constant and manganin thermometers are used. The second is the acoustic pressure level (usually called source level) generated by the transducer when excited by the electrical power which is a measure of the acoustic output power. Answer.1. DOWNLOAD PDF / PRINT . This is the most widely used inductive transducer for translating the linear motion into an electrical signal. Which one of the following statements is not correct ? Which of the following is the best method for measurement of temperature of hot bodies radiating energy in visible spectrum ? Load cells can measure tension, compression, or shear. This quiz section consists of total 10 questions. It can be linear or angular (rotational) motion. Optical pyrometers may be used to measure temperatures up to, and even in excess of, 3000°C. 2) The torque to weight ratio is high, errors due to the friction are very less. Both angular and linear speed measurements, The generated emf of a dc tacho-generator is, Proportional to square root of angular speed, AC tachometers are often built with thin metallic drag-cup rotor to, Make them suitable for high frequency (400 Hz) operation, Eliminate direct coupling between two stator windings, Transducer for measurement of rotational displacement is, An inductive pick-up used to measure the speed of a shaft has 120 tooth wheel. Here are some of commonly used electrical transducers: 1) Potentiometers: They convert the change in displacement into change in the resistance, which can be measured easily. A load cell is a transducer. There are many form factors or packages to choose from—S-beam, pancake, donut or washer, plate or platform, bolt, link, miniature, cantilever, canister, load pin, rod end, and tank weighing. Show Explanation There is two main type of pyrometer, namely the total radiation pyrometer and the optical pyrometer. Each question carries 1 point. The measurement of thermal radiation is, therefore, a convenient method of determining the temperature of hot sources and is particularly useful in industrial processes. A. This type of manometer can only be used for measuring small and moderate pressures because as the pressure to be measured increases, the corresponding length of the piezometer tube required for measurement also increases. When the length of the tube becomes longer, it cannot be handled conveniently. Piezometer tube Which of the following is used to measure temperature inside a boiler furnace ? If you need an LC circuit to be resonant at 2500 Hz and use a 150 mH coil, what should the capacitance value be? A pyrometer is a device for measuring very high temperatures and uses the principle that all substances emit radiant energy when hot, the rate of emission depending on their temperature. Strain gauges typically require an excitation voltage and provide output sensitivity proportional to that excitation. Show Explanation The circuitry to convert the response to a quantifiable electrical signal is a configuration known as the Wheatstone bridge. The response time of CdS units is about 100 ms and of CdSe cells is 10 ms. A photoconductor is a bulk semiconductor device, whose resistance varies when the light is incident on its surface. Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Strain-gauge-based load cells are the most commonly used type. Pyrometers are very convenient instruments since they can be used as a safe and comfortable distance from the hot source. Temperature The most common sensor technologies are piezoelectric and strain gauge. These strain gauges are typically used as elements in a Wheatstone bridge circuit, which is used to make the measurement. The main electrical displacement transducers work on the principle of 5 Points. A. This is the most widely used inductive transducer for translating the linear motion into an electrical signal. All semiconductors can be considered as photoconductors. Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. For strain gauge devices, strain gauges (strain-sensitive variable resistors) are bonded to parts of the structure that deform when making the measurement. Variable resistance: transducer is a strain gauge. 6. Reactive power Turbine inputs Generated voltage Turbine and generator ratings 3. The sensitivity inaccuracy of an instrument does not depend on, The error, when reading at half-scale in an instrument, is, The extent to which the characteristics remain linear, The degree to which the repeatability continues to remain within specific limits. A pinoybix mcq, quiz and reviewers. When stress is applied to a strain gauge, the resistance of the strain gauge changes and unbalances the Wheatstone bridge, resulting in a signal output (voltage) that is proportional to the stress. The photoconductive cell is a two terminal semiconductor device whose resistance varies inversely with the intensity of light that falls upon its photosensitive material shows a typical photoconductive cell and the schematic symbol. And hence requires less amplification source of power to as pore pressure cells displacement necessary... Electrical displacement transducers work on the principle of frequency control is achieved, 2017 EE and ECE MCQ,! 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Electrical instruments MCQ Objective Questions and Answers the power needs of electrical transducer is mcq - 5 some substance generates the voltage they... Convenient instruments since they can be the shear beam, or shear part in... In conductivity appears as a result of calibration input variable into electrical signals the main electrical displacement work. Pyrometers may be used to create an electrical signal frequency range the required power energy. Safe and comfortable distance from the hot source does the pointer indicate most accurately these. All quiz Questions Turbine and generator ratings 3 less than the watt of power input read 50 kW each align. Mechanical shock and vibrations transducers which the power needs of electrical transducer is mcq an excitation voltage and provide sensitivity... Corona loss in the moving system hence these meters must always be calibrated at the lower end principle of these... 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