Rayleigh Scattering

Definition: Rayleigh scattering is the phenomena of scattering of light particles majorly by the molecules of gas (sometimes also by solid and liquid). This scattering of light was first noticed by Lord Rayleigh in 1871 and thus named so. Basically when electromagnetic light propagates through air, then the back and forth movement of electrons inside the…

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Optical Time Domain Reflectometer (OTDR)

Definition: OTDR is an acronym used for Optical Time Domain Reflectometer. It is an instrument that is used to detect or analyze the scattered or back reflected light through an optical fiber due to impurities and imperfections in the fiber. The operating principle of an OTDR is similar to that of radar. OTDR performs timed…

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Splicing of Optical Fibers

Definition: Splicing of optical fibers is a technique used to join two optical fibers. This technique is used in optical fiber communication, in order to form long optical links for better as well as long-distance optical signal transmission. Splicers are basically couplers that form a connection between two fibers or fiber bundles. At the time…

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Voltage Doubler

Definition: A multiplier circuit that generates a dc output voltage having amplitude twice the maximum amplitude of the ac input supply voltage is known as Voltage Doubler. The circuit shows its necessity in all such applications where a high level of voltage is required when the input source is of low amplitude. Here, the name…

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Varistor

Definition: A varistor is a 2 terminal semiconductor device that protects the electrical and electronic devices from overvoltage transients. Its resistance is dependent on the applied input voltage. The word varistor is formed by the combining variable and resistor. It is also known as voltage-dependent resistor, VDR whose resistance changes automatically with the corresponding change in…

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Laser Diode

Definition: A semiconductor device that generates coherent light of high intensity is known as laser diode. LASER is an abbreviation for Light Amplification by Stimulated Emission of Radiation. Stimulated emission is the basis of working of a laser diode. Laser diode is similar to LED, however, different from LED, the PN junction of laser diode…

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Photodiode

Definition: A special type of PN junction device that generates current when exposed to light is known as Photodiode. It is also known as photodetector or photosensor. It operates in reverse biased mode and converts light energy into electrical energy. The figure below shows the symbolic representation of a photodiode: Principle of Photodiode It works…

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Difference Between Transducer & Inverse Transducer

One of the major difference between the transducer and the inverse transducer is that the transducer changes the non-electrical quantity into an electrical quantity while the inverse transducer changes the electrical quantity into the non-electrical quantity. The other differences between the transducer and inverse transducer are shown below in the comparison chart. The control action…

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Difference Between AC & DC Bridge

One of the significant difference between the AC and DC bridge is that the AC bridge is used for measuring the unknown impedance of the circuit whereas the DC bridge is used for measuring the unknown resistance of the circuit. The other differences between the AC and DC bridge are shown below in the comparison…

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Electrostatic Instrument

Definition: The instrument whose working depends on the principle of attraction or repulsion of electrodes that carry electrical charges such type of instrument is known as the electrostatic instrument. In other words, the instrument which uses the static electric field for producing the deflecting torque is known as the electrostatic instrument. The electrostatic instrument is…

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