For piezoelectric devices, a piezoelectric material is compressed and generates a charge that is conditioned by a charge amplifier. A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. Repulsion type Moving instruments— These instruments are based on the principle of repulsion between the two iron pieces similarly magnetized. The response time of CdS units is about 100 ms and of CdSe cells is 10 ms. Show Explanation Assuming generators and transmission network to be lossless, the system frequency for a load of 700 … By matching which of the following individual machines, the load frequency control is achieved? Electrical and Electronics Measurement & Instrumentation Expected MCQ PDF 6 For VIZAG Exam 2017. Chapter 15 Multiple choice questions and answers. Strain gauges typically require an excitation voltage and provide output sensitivity proportional to that excitation. They derive the required power for energy change from an exterior power source. Hence accurate readings are not possible at this end. The two wattmeters used for the measurement of power input read 50 kW each. Variable resistance: transducer is a strain gauge. Ruggedness: The LVDT is mechanically rugged and can withstand mechanical shock and vibrations. 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. Torque weight ratio will be least in ___________  instruments. 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. 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. Answer.1. Narrow bandwidth and low accuracy are required/sufficient. Ques.64. Answer.1. A power factor meter has  ____________  control springs. Explanation:- 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. The transducers convert the physical forces into an electrical signal which can easily be handled and transmitted for measurement. Pyrometers are very convenient instruments since they can be used as a safe and comfortable distance from the hot source. It is quite difficult to determine the exact magnitude of the physical forces like temperature, pressure, etc. In the figure, the pressure at the point above atmospheric pressure is: hA  is the height of the liquid column in the piezometer tube. Acting as a secondary transducer, LVDT can be used as a device to measure force, weight & pressure etc. Show Explanation Tension cells are used for measurement of a straight-line force ‘pulling apart’ along a single axis; typically annotated as the positive force. 5) There is a difference between a.c and d.c calibrations on account of the effect of the inductance of the meter. An active transducer directly converts input variable into electrical signals. δE = Limiting error For example photovoltaic cell in which light energy is converted into electrical energy. Load cells can measure tension, compression, or shear. 2) There are serious errors due to hysteresis, frequency changes, and stray magnetic fields. 2) The torque to weight ratio is high, errors due to the friction are very less. Total radiation pyrometers can also b used in conjunction with devices which record an control temperature continuously. ‣ 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. D. Codify/decodify the input signal. 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. Thus applications of pyrometer are found in measuring the temperature of molten metals, the interiors of furnaces or the interiors of volcanoes. Load cells can measure tension, compression, or shear. δE = ±5mv 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. Between 1000°C and 1600°C Platonism Rhodium thermocouple is used. Variable inductance: transducer is a linear variable differential transformer Which of the following quantities cannot be measured by a load cell? In the figure, the pressure at the point above atmospheric pressure is: 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 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. Temperature You can get the Quiz Answers after submitting all quiz questions. 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. LINEAR VARIABLE DIFFERENTIAL TRANSFORMER (LVDT) 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. Hence these meters must always be calibrated at the frequency at which Hey are to be used. Participate in the Sanfoundry Certification contest to get free Certificate of Merit. 3) A single type of moving element can cover the wide range hence this instrument; are cheaper than other types of instruments. There is two main type of pyrometer, namely the total radiation pyrometer and the optical pyrometer. Since the other end of the tube is open to atmosphere, the pressure obtained using the piezometer tube is gauge pressure. Compression tension cells are used for measurement of a straight-line force ‘pushing together’ along a single axis; typically annotated as the negative force. A hot-wire anemometer is a device used to measure  : The device used for measuring flow of air around an aeroplane is. Ques.61. 6) These can withstand large loads and are not damaged even under severe overload conditions; 7) The range of instruments can be extended. i.e., 1mm displacement of the care produces an output voltage of 300 mV. Photoconductive cell Proportional to transmission voltage B. Wide bandwidth and low accuracy are required/sufficient. Explanation:- A gallium boiling point 1700°C thermometer made of quartz can be conveniently used for measurement of temperature upto 1000°C. cause  __________ errors. The resistive type mainly includes a thermistor, resistance strain gauge, and photoconductive cell. However, this interference can be reduced by shielding. A pinoybix mcq, quiz and reviewers. Which one of the following pressure transducers is suitable for measurement of high pressure  ? Which if the following moving particles cannot be deflected by magnetic fields  ? Es = Specified or rated value They are sensitive to stray magnetic fields. Ques.65. which will improve your skill. Explanation:- 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. is connected in. Function of transducer is to convert A. Strain gauge-based load cells have a sensing junction/element that when loaded responds to the load by producing an electrical output. The actual value of limiting error can be expressed as ... 406. This is because any semiconductor will produce electron-hole pairs (EHP) when it is irradiated by electromagnetic radiation of the optical frequencies. 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). The main electrical displacement transducers work on the principle of Strain Gauge Load Cell 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. Modify the input signal. 31. Changes in atmospheric temperature, humidity etc. 2. Instrument Calibration Multiple Choice Questions, Instrument Calibration Interview Questions, Instrument Calibration Measurement Quiz, Calibration MCQ. Answer.1. 5) These are capable of giving good accuracy. Electrical signal into non electrical quantity B. Which of the following is used to measure temperature inside a boiler furnace  ? The photoconductive materials most frequently used include cadmium sulfide (CdS) and cadmium selenide (CdSc). Transducers which require an external power source for their operation is called as a passive transducer. Wide  bandwidth and high accuracy are required. 1. Attraction type moving instrument. The accuracy of a 0-100 mV voltmeter is ±5%. 1) The scale of the moving iron instruments is not uniform and is cramped at the lower end. 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. Using nitrogen in place of hydrogen in Rhodium bulb, the temperature as high as 1600°C can be measured. Amplify the input signal. Which is the most suitable thermocouple transducer for the measurement of temperature in the range of 1,000C  to  1,5000C  ? These strain gauges are typically used as elements in a Wheatstone bridge circuit, which is used to make the measurement. PA = whA  Which of the following thermocouple pairs has maximum sensitivity around 273 K  ? Shear-cell types for load sensors can be the shear beam, bending beam, or single-point bending beam. Vibrating reeds are used in which of the following instruments? 3) A single type of moving element can cover the wide range hence this instrument; Comparatively, large displacement is necessary for appreciable differential output. No negative points for wrong answers. 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. Least expensive instrument for dc measurements is, Answer.3. Also, to reduce the surface tension and capillarity effects. For measuring electric charges; As null – point detectors in ac bridges; As null – point detectors in dc bridges; For measuring power; Ans. Which of the following transducers is most suitable for monitoring continuous variations in very fine thickness of a material  ? Ques.70. Ea = Actual value Answer.4. Need help preparing for your electrical exams? Morningexam.com provides Electrical MCQs, Notes, Exam Materials and Online Test series for your Competitive exams. Each question carries 1 point. Thermoelectric pyrometer Show Explanation Active transducers do not require any external source of power for their operation. This transducer is also named as an externally power-driven transducer. Variable resistance: transducer is a strain gauge. The main electrical displacement transducers work on the principle of. Isolation transformer transfer electrical power from the source circuit to another circuit with connecting electrically (but magnetically) for preventing electric shock and also used in sensitive devices (like medical equipment etc). The principle of operation of variable resistance transducer is Piezometers are used to monitor pore water pressure and are sometimes referred to as pore pressure cells. The tube is kept vertical and its other end is open to atmosphere. Answer: Option C MCQ in Industrial Electronics Part 2 of the series as Electronics Engineering topic in ECE Board Exam. These strain gauges are typically used as elements in a Wheatstone bridge circuit, which is used to make the measurement. All semiconductors can be considered as photoconductors. Scintillation counters have the advantage(s) of, Capability of detecting of radiations of lower levels, Analog data acquisition system are used when. 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). The Helium. It comprises of a detecting / sensing element and a transduction element. 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.  High temperature: For high-temperature measurement upto 500°C the standard hydrogen gas thermometer with platinum-iridium bulb can be used, and for the temperature upto 1100°C porcelain bulb is used. the diameter of the tube must be at least 12 mm. Depending upon the principle of transduction, they are further classified as: Electromagnetic MCQ in Electrical Circuit part 9 as part of the Electronics Engineering Board Exam. These include frequencies in the infrared, visible and ultraviolet radiations. 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. For strain gauge devices, strain gauges (strain-sensitive variable resistors) are bonded to parts of the structure that deform when making the measurement. Optical pyrometer is generally used to measure, The flow rate of electrically conducting liquid without any suspended particle cannot be measured by. They are stable and easy to align and maintain. Show Explanation B. 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. Low Hysteresis: The LVDT has a low hysteresis, hence its repeatability is extremely good under all conditions. All of the given option are correct, LINEAR VARIABLE DIFFERENTIAL TRANSFORMER (LVDT). Thermoelectric-thermometer where Since the other end of the tube is open to atmosphere, the pressure obtained using the piezometer tube is gauge pressure. 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. Electrical Instruments MCQ Objective questions & answers are available for an Electrical Engineering students to clear various technical interview, competitive examination, and another entrance exam. The attenuation and amplification of the electrical signals are very e… Multiple-Choice Questions. 1. Answer.4. The power, connector and protocol for these EVSE will vary based on it design which we will discuss in this article. 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 … The photoconductive materials most frequently used include cadmium sulfide (CdS) and cadmium selenide (CdSc). These include frequencies in the infrared, visible and ultraviolet radiations. Further, these transducers are classified into resistive, capacitive and inductive. The measurement of thermal radiation is, therefore, a convenient method of determining the temperature of hot sources and is particularly useful in industrial processes. 4) There is no current-carrying part; in the moving system hence these meters are extremely rugged and reliable. 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.2. 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. Piezometer tube ANSWER: Potentiometer. The circuitry to convert the response to a quantifiable electrical signal is a configuration known as the Wheatstone bridge. Load cells typically contain multiple strain gauges aligned and wired in a Wheatstone bridge circuit. Answer.4. Same as a photovoltaic cell a Matching layer. 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. Very low pressure ... You may also need. Also, to reduce the surface tension and capillarity effects. Pyrometers are very convenient instruments since they can be used as a safe and comfortable distance from the hot source. DOWNLOAD PDF / PRINT . Various types of load cells include hydraulic load cells, pneumatic load cells, and strain gauge load cells. Best for ITI and Diploma Students. 2. Synchros and resolvers: used to measure angular displacement Measurement of temperature using the thermometer. Which one of the following statements is not correct  ? 1․ A power system has three synchronous generators. Reactive power Turbine inputs Generated voltage Turbine and generator ratings 3. A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. 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. 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. b Doppler effect. Most load cells actually measure the displacement of a structural element to determine force. 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. 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. However, this interference can be reduced by shielding. A pinoybix mcq, quiz and reviewers. They are sensitive to stray magnetic fields. The dynamic response is limited. Strain gauges typically require an excitation voltage and provide output sensitivity proportional to that excitation. The transducer is classified by the transduction medium. Show Explanation This is the most widely used inductive transducer for translating the linear motion into an electrical signal. With the help of the displacement transducer, many other quantities, such as force, stress, pressure, velocity, and acceleration can be found. The range can be increased to 600°C by filling the space above mercury with some inert gas. Gas thermometers A transducer is a device that converts energy from one form to another. Explanation:- 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 height of the liquid in the tube above any point in the fluid indicates the pressure of the liquid at that point. Explanation:- Shear-cell types for load sensors can be the shear beam, bending beam, or single-point bending beam. Variable capacitance: transducer is a parallel plate capacitor with a variable gap Most load cells actually measure the displacement of a structural element to determine force. Where Explanation:- transducers are used for the measurement of a pressure b displacement c humidity d both a and b view answer hide answer answer d both a and b q3 thermistor is a transducer its temperature coefficient is a negative, multiple choice questions and answers on antenna amp wave propagation objective questions and answers on antenna amp wave High temperature: A mercury thermometer (boiling point of mercury is 357°C) can be used to measure temperature upto 300°C. Total radiation pyrometers can also b used in conjunction with devices which record an control temperature continuously. The power transmission capacity of a transmission line is . Total radiation pyrometers are used to measure temperature in the range 700°C to 2000°C. Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. 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. If you need an LC circuit to be resonant at 2500 Hz and use a 150 mH coil, what should the capacitance value be? Less friction: Since there is no sliding contact, the friction is very less. The tube is kept vertical and its other end is open to atmosphere. The limiting error at full scale is Strain gauges are made up of a long, thin strip of conductive material arranged in a zigzag manner. A. Natural piezoelectric materials such as quartz (SiO2) and Rochelle salt (NaKC4H4O6–4H2O) are also used for piezoelectric transducers. High Output: The LVDT gives reasonably high output and hence requires less amplification. Piezoelectric Thus applications of pyrometer are found in measuring the temperature of molten metals, the interiors of furnaces or the interiors of volcanoes. Such substance is known as. 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: Applications of LVDT 6) Power consumption is on the higher side. The most common sensor technologies are piezoelectric and strain gauge. A. All semiconductors can be considered as photoconductors. 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 is the most widely used inductive transducer for translating the linear motion into an electrical signal. Some substance generates the voltage when they are subjected to mechanical forces or stress along specific planes. For strain gauge devices, strain gauges (strain-sensitive variable resistors) are bonded to parts of the structure that deform when making the measurement. 4) Due to the non-linearity of the B-H curve, the deflecting torque is not exactly proportional to the square of the current. 6. The corona loss in the transmission line can be reduced by increasing spacing between the conductors or the diameter of the conductors. It is used to create an electrical signal whose magnitude is directly proportional to the force being measured. Optical pyrometers may be used to measure temperatures up to, and even in excess of, 3000°C. The accuracy of a meter is determined by  ____________  deflection. The function of a transducer is to. 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. 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. Answer.4. 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. 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. Low Power Consumption: Most LVDTs consume Less than the watt of power. Explanation:- Strain-gauge-based load cells are the most commonly used type. Phosphor bronze can be used to measure still lower temperatures with great accuracy. Explanation:- 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.) II) Electrical Transducers. You can also get Current Affairs, GK, Aptitude, Verbal Ability, and Reasoning questions. Proportional to the square of transmission voltage C. Inversely proportional to the transmission voltage D. Inversely proportional to the square of transmission voltage Comparatively, large displacement is necessary for appreciable differential output.