Photoelectric Transducer

Definition: The photoelectric transducer converts the light energy into electrical energy. It is made of semiconductor material. The photoelectric transducer uses a photosensitive element, which ejects the electrons when the beam of light absorbs through it. The discharges of electrons vary the property of the photosensitive element. Hence the current induces in the devices. The…

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Hygrometer

Definition: Hygrometer uses for measuring the humidity present in the surrounding environment. The term humidity means the amount of water vapour present in the gas. The physical properties of the material changes by the effect of the humidity and this principle use in hygrometer for measurement. The humidity is classified into two types. Absolute Humidity…

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Schering Bridge

The Schering bridge use for measuring the capacitance of the capacitor, dissipation factor, properties of an insulator, capacitor bushing, insulating oil and other insulating materials. It is one of the most commonly used AC bridge. The Schering bridge works on the principle of balancing the load on its arm. Let, C1 – capacitor whose capacitance…

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Kelvin Bridge

Definition: The Kelvin bridge or Thompson bridge is used for measuring the unknown resistances having a value less than 1Ω. It is the modified form of the Wheatstone Bridge. What is the need of Kelvin Bridge? Wheatstone bridge use for measuring the resistance from a few ohms to several kilo-ohms. But error occurs in the…

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Volt-Ohm-Milli-Ammeter (VOM)

Definition: The multimeter or volt-ohm-milli-ammeter (VOM) is the type of meter which performs the multiple functions. In other words, in VOM the multiple measuring functions are combined in a single unit. The multimeter is used for measuring voltage, current and resistance. It contains the circuitry switch which makes the meter to operate like a voltmeter,…

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Thermocouple

Definition: The thermocouple is a temperature measuring device. It uses for measuring the temperature at one particular point. In other words, it is a type of sensor used for measuring the temperature in the form of an electric current or the EMF. The thermocouple consists two wires of different metals which are welded together at…

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Limiting Error

Definition: The limited deviation of the measured value from the true value is known as the limiting error or guarantee error. Such type of error is fixed on the instrument. The magnitude of the limiting error depends on the design, material and the workmanship used for the construction of the instrument. For obtaining a high degree…

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Differential Voltmeter

Definition: The voltmeter which measures the difference between the known and the unknown voltage source is known as the differential voltmeter. It works on the principle of comparison between the reference and the unknown voltage sources. The accuracy of the differential voltmeter is very high.The principle of operation of the differential voltmeter is similar to…

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Rectifier Type Instrument

Definition: The instrument which uses the rectifying element for measuring the voltage and current is known as the rectifying instruments. The rectifying element converts the alternating current to the direct current which indicates by the DC responsive meter. The PMMC uses as an indicating instrument. The sensitivity of the rectifying instruments is high as compared…

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Classification of Measuring Instruments

The instrument used for measuring the physical and electrical quantities is known as the measuring instrument. The term measurement means the comparison between the two quantities of the same unit. The magnitude of one of the quantity is unknown, and it is compared with the predefined value. The result of the comparison obtained regarding numerical…

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