Optical pyrometers may be used to measure temperatures up to, and even in excess of, 3000°C. Thus applications of pyrometer are found in measuring the temperature of molten metals, the interiors of furnaces or the interiors of volcanoes. Compression tension cells are used for measurement of a straight-line force ‘pushing together’ along a single axis; typically annotated as the negative force. Strain gauge-based load cells have a sensing junction/element that when loaded responds to the load by producing an electrical output. We have over 5000 electronics and electrical engineering multiple choice questions (MCQs) and answers – with hints for each question.. Electrical4U’s MCQs are in a wide range of electrical engineering subjects including analog and digital communications, control systems, power electronics, electric circuits, electric machines – and much … There is two main type of pyrometer, namely the total radiation pyrometer and the optical pyrometer. Show Explanation 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. 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. Modify the input signal. Strain-gauge-based load cells are the most commonly used type. Assuming generators and transmission network to be lossless, the system frequency for a load of 700 … 105 mV or 95 mV δE = Limiting error 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. For piezoelectric devices, a piezoelectric material is compressed and generates a charge that is conditioned by a charge amplifier. Piezometer tube In this page you can learn various important potentiometer multiple choice questions answers,mcq on potentiometer with answers,mcq on potentiometer,sloved potentiometer objective questions answers, potentiometer multiple choice questions answers etc. They are sensitive to stray magnetic fields. The circuitry to convert the response to a quantifiable electrical signal is a configuration known as the Wheatstone bridge. The most common sensor technologies are piezoelectric and strain gauge. 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). Hence accurate readings are not possible at this end. The photoconductive materials most frequently used include cadmium sulfide (CdS) and cadmium selenide (CdSc). Proportional to transmission voltage B. The power transmission capacity of a transmission line is . 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-gauge-based load cells are the most commonly used type. is connected in. 2. Less friction: Since there is no sliding contact, the friction is very less. Which of the following instruments may be used to measure DC voltage accurately? Such substance is known as. 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. An EVSE is designed and engineered to charge a battery pack by using the grid for Power Delivery; these battery packs might be present in an Electric Vehicle (EV) or in a Plug-in Electric Vehicle (PEV). 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. Repulsion type Moving instruments— These instruments are based on the principle of repulsion between the two iron pieces similarly magnetized. ... You may also need. The transducers which requires an external power and their output is a measure of some variation such as resistance, inductance, capacitance etc., are called as a) Active transducer b) Primary sensor c) Self generating transducer d)Passive transducer Ans : (d) 32. Thermoelectric pyrometer MCQ in Electrical Circuit part 9 as part of the Electronics Engineering Board Exam. A load cell is a transducer. Which of the following improves sound transmission from the transducer element into the tissue? Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. In AC bridge if the supply frequency is 1000 Hz, the detector will be. With the help of the displacement transducer, many other quantities, such as force, stress, pressure, velocity, and acceleration can be found. Strain gauges are made up of a long, thin strip of conductive material arranged in a zigzag manner. Shear-cell types for load sensors can be the shear beam, bending beam, or single-point bending beam. For strain gauge devices, strain gauges (strain-sensitive variable resistors) are bonded to parts of the structure that deform when making the measurement. The time required by an instrument to begin to respond to a change in the measurand, The time required by an instrument for initial warming up, The largest change of input quantity for which there is no output of the instrument, In resistance thermometers platinum is used because of, Low cost, high stability and wide operating range. Strain gauges are made up of a long, thin strip of conductive material arranged in a zigzag manner. 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 Advantages of LVDT: The actual value of limiting error can be expressed as Since the other end of the tube is open to atmosphere, the pressure obtained using the piezometer tube is gauge pressure. Best for ITI and Diploma Students. 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.) Modern moving iron instruments have a d.c. an error of 2% or less. Using nitrogen in place of hydrogen in Rhodium bulb, the temperature as high as 1600°C can be measured. PHOTOCONDUCTIVE CELLS Shear is induced by tension or compression along offset axes. High temperature: A mercury thermometer (boiling point of mercury is 357°C) can be used to measure temperature upto 300°C. Explanation:- Low temperature: For measurements of low temperatures upto −250°C constant volume hydrogen thermometers are used and for measure merits below -250°C upto -270°C hydrogen is replaced by Helium. In electrical measuring instruments, electrical energy is converted to, Sensitivity of a voltmeter is given by the, Reciprocal of full scale deflection current, In the case of indicating instruments the function of the control spring is, To pass electric current to moving system. The main electrical displacement transducers work on the principle of For piezoelectric devices, a piezoelectric material is compressed and generates a charge that is conditioned by a charge amplifier. Which is the most suitable thermocouple transducer for the measurement of temperature in the range of 1,000C  to  1,5000C  ? With the help of the displacement transducer, many other quantities, such as force, stress, pressure, velocity, and acceleration can be found. Strain Gauge Load Cell Ques.69. 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. Answer.2. 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 tube is kept vertical and its other end is open to atmosphere. The measurement of thermal radiation is, therefore, a convenient method of determining the temperature of hot sources and is particularly useful in industrial processes. The usual commercial moving iron instrument may be used within its specified accuracy from 25 to 125 Hz frequency range. Between 1000°C and 1600°C Platonism Rhodium thermocouple is used. ‣ Multiple Choice Question (MCQ) of Power Systems page-21 ‣ Multiple Choice Question (MCQ) of Power Systems page-20 ... Hydro-electric power plant c) Atomic Reactor d) MHD Ans: (c) 65. Ques.64. A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. δE = ± 5% of 100 Piezometers are used to monitor pore water pressure and are sometimes referred to as pore pressure cells. 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. 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. 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. A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. δE = ±5mv 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. LINEAR VARIABLE DIFFERENTIAL TRANSFORMER (LVDT) 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. Show Explanation Compression tension cells are used for measurement of a straight-line force ‘pushing together’ along a single axis; typically annotated as the negative force. Optical pyrometer is generally used to measure, The flow rate of electrically conducting liquid without any suspended particle cannot be measured by. C. Convert the primary signal into a more useful quantity, usually an electric impulse. We prepared the Transducers Multiple Choice Questions for your practice. Electrical and Electronics Measurement & Instrumentation Expected MCQ PDF 6 For VIZAG Exam 2017. In which part of the scale does the pointer indicate most accurately? 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. Which of the following thermocouple pairs has maximum sensitivity around 273 K  ? 3) A single type of moving element can cover the wide range hence this instrument; are cheaper than other types of instruments. 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. Since deflection θ is proportional to the square of current through the coil, therefore scale of such instruments in non-uniform being crowded in the beginning. Ques.70. Narrow bandwidth and low accuracy are required/sufficient. Also, to reduce the surface tension and capillarity effects. The piezometer, when used for the measurement of pressure in a pipe in which fluid is flowing, must be kept such that the axis of the tube is normal to the direction of flow. Answer.4. The corona loss in the transmission line can be reduced by increasing spacing between the conductors or the diameter of the conductors. Resistance thermometers Variable resistance: transducer is a strain gauge. All of the given option are correct, LINEAR VARIABLE DIFFERENTIAL TRANSFORMER (LVDT). Generally, a transducer with an mV electrical output can be used in laboratory applications. Total radiation pyrometers are used to measure temperature in the range 700°C to 2000°C. at the pressure below its vapor pressure can be used to measure temperature down to 1 K. But if the physical force is converted into an electrical signal, then their value is easily measured with the help of the meter. Electrical signal into non electrical quantity B. Optical pyrometers may be used to measure temperatures up to, and even in excess of, 3000°C. Since the other end of the tube is open to atmosphere, the pressure obtained using the piezometer tube is gauge pressure. Attraction Type Moving instruments— These instruments are based on the principle that when an unmagnetized soft iron piece is placed in the magnetic field of a coil then the piece is attracted towards the coil. Load cells can measure tension, compression, or shear. Liquid thermometer:-  _____________  bridge is used for the precise measurement of inductances over a wide range. The range can be increased to 600°C by filling the space above mercury with some inert gas. 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. This transducer is also named as an externally power-driven transducer. Explanation:- 4) There is no current-carrying part; in the moving system hence these meters are extremely rugged and reliable. It is used to create an electrical signal whose magnitude is directly proportional to the force being measured. Piezoelectric Low Power Consumption: Most LVDTs consume Less than the watt of power. Being relatively inexpensive, reliable and rugged in construction. When the load power factor is unity, the effect of armature reaction on the main field flux of an alternator is distortional magnetizing demagnetizing no effect 2. PA = whA  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. Function of transducer is to convert A. 1․ A power system has three synchronous generators. The force is associated with a deflection as a result of calibration. Where Answer: Option C Answer.1. Es = Specified or rated value with copper, Same resistance temperature co-efficient as the coil of the instrument, Been annealed properly so that its resistance does not change with time, Meter ranges are so selected that the indications are obtained near the, For measuring an unknown electrical quantity, select the meter with, With middle range and work up and down on trial and error basis, Moving iron meters are extensively used for the measurement of AC voltage and current because, No current flows through the moving element and is robust, Moving iron instruments are rarely used in low power high resistance circuits because of, Scale of an instrument will ne uniform if, Deflecting torque varies directly as the deflection angle, Control torque varies directly as the deflection angle, Damping torque varies directly as the deflection angle, Compensate the error due to temperature variations, Compensate the error due to strong magnetic field. Most load cells actually measure the displacement of a structural element to determine force. A strain gauge is a passive transducer … Explanation:- Acting as a secondary transducer, LVDT can be used as a device to measure force, weight & pressure etc. Thermoelectric-thermometer 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. Need help preparing for your electrical exams? Ruggedness: The LVDT is mechanically rugged and can withstand mechanical shock and vibrations. The tube is kept vertical and its other end is open to atmosphere. The photoconductive materials most frequently used include cadmium sulfide (CdS) and cadmium selenide (CdSc). High-temperature range: Platinum resistance thermometers can be used to measure temperature upto 700°C with the coil enclosed in the glass bulb and lead made of copper and upto 1300°C with the coil enclosed in porcelain with platinum leads. Transducers which require an external power source for their operation is called as a passive transducer. 1) The scale of the moving iron instruments is not uniform and is cramped at the lower end. Changes in atmospheric temperature, humidity etc. The main electrical displacement transducers work on the principle of. Variable resistance: transducer is a strain gauge. The force is associated with a deflection as a result of calibration. High Output: The LVDT gives reasonably high output and hence requires less amplification. The dynamic response is limited. Explanation:- Transducer - MCQs with answers Q1. Strain gauges typically require an excitation voltage and provide output sensitivity proportional to that excitation. It is quite difficult to determine the exact magnitude of the physical forces like temperature, pressure, etc. 2) There are serious errors due to hysteresis, frequency changes, and stray magnetic fields. There is two main type of pyrometer, namely the total radiation pyrometer and the optical pyrometer. This quiz section consists of total 10 questions. Pyrometers are very convenient instruments since they can be used as a safe and comfortable distance from the hot source. A lead thermometer may be used to measure temperature as low as -250°C and below these temperature constant and manganin thermometers are used. You can also get Current Affairs, GK, Aptitude, Verbal Ability, and Reasoning questions. The most common sensor technologies are piezoelectric and strain gauge. It is used to create an electrical signal whose magnitude is directly proportional to the force being measured. Proportional to the square of transmission voltage C. Inversely proportional to the transmission voltage D. Inversely proportional to the square of transmission voltage 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. The transducer is classified by the transduction medium. Disadvantages of LVDT Jan 02,2021 - HVDC Of Power Systems | 10 Questions MCQ Test has questions of Electrical Engineering (EE) preparation. Q98. Variable inductance: transducer is a linear variable differential transformer Usually a transducer converts a signal in one form of energy to a signal in another.. Transducers are often employed at the boundaries of automation, measurement, and control systems, where electrical signals are converted to and from other physical quantities (energy, force, torque, light, motion, position, etc. This is the most widely used inductive transducer for translating the linear motion into an electrical signal. 6) Power consumption is on the higher side. Synchros and resolvers: used to measure angular displacement It can be linear or angular (rotational) motion. The limiting error at full scale is If the number of pules produced in a second is 3000, the rpm of the shaft is, Doppler shift principle is used in the measurement of, The accelerometer using  LVDT  has the advantage of, The accelerometer used for measurement of vibration of large structures is, The most common transducer for shock and vibration measurement is, The drawbacks of radiation pyrometers are that, Their initial as well as installation costa are high, Each pyrometer needs individual calibration, In optical pyrometers temperature is measured by. Show Explanation Participate in the Sanfoundry Certification contest to get free Certificate of Merit. For example, a photocell (LDR) is a passive transducer which will vary the resistance … 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. 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. Least expensive instrument for dc measurements is, Answer.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. II) Electrical Transducers. Comparatively, large displacement is necessary for appreciable differential output. 1. 1. For strain gauge devices, strain gauges (strain-sensitive variable resistors) are bonded to parts of the structure that deform when making the measurement. Morningexam.com provides Electrical MCQs, Notes, Exam Materials and Online Test series for your Competitive exams. Piezoelectric materials can act as transducers, Quarz crystal is a ferroelectric material, The dielectric constant of dielectrics depends on the frequency of the applied field. Load cells can measure tension, compression, or shear. The circuitry to convert the response to a quantifiable electrical signal is a configuration known as the Wheatstone bridge. 5) These are capable of giving good accuracy. 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. Wide bandwidth and low accuracy are required/sufficient. 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). 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And Rochelle salt ( NaKC4H4O6–4H2O ) are also called photoresistive cells or photoresistors since the end! Include hydraulic load cells have a sensing junction/element that when loaded responds to the non-linearity of the series as Engineering! Following statements is not correct matching which of the scale of the liquid at point! Example photovoltaic cell in which part of the liquid at that point with turns ratio of 1:1 good!