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Found 84 Articles for Miscellaneous
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Concept of Electromotive Force (EMF)The electromotive force (EMF) of a source, is a measure of the energy the source gives to each coulomb of charge. The EMF is measured in volts (V).At first sight, the name EMF implies that it is a force that causes the current to flow but this not correct, because it is not a force but energy supplied to the charge by some source of energy such as a battery. The EMF maintains potential difference while the potential difference causes current to flow.Difference between EMF and Potential DifferenceAs we know, the EMF of the battery is ... Read More
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The superposition theorem is used in solving a network in which two or more sources are present and connected not in series or in parallel.Statement of Superposition TheoremIf two or more voltage or current sources are acting simultaneously in a linear network, the resultant current in any branch is the algebraic sum of the currents that would be produced in it, when each source acts alone and all other independent sources are replaced by their internal resistances.Explanation of Superposition TheoremIn the circuit given below, we have to find the branch currents viz. i1, i2, i3 by using superposition theorem.Step 1 ... Read More
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A Voltaic cell is an electrochemical cell that converts the chemical energy of spontaneous (natural) redox reactions into electrical energy. The Voltaic cell is also called as Galvanic cell.The voltaic cell is named after its inventor Alessandro Volta in 1799.In redox (oxidation-reduction) reactions, the electrons are moved between two different species and if these reactions occur spontaneously then energy is released as a result of these reactions. Therefore, the released energy is used to do work. To deal with this energy, it is necessary to split the reaction into two half reactions – Oxidation and Reduction. By using two different ... Read More
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ResistorThe measure of opposition offered by the substance in the flow electric current is known as Resistance of the substance and the element that possess the resistance is called a Resistor. The circuit symbol of resistor is shown in the figure below.Types of ResistorsThe resistor are broadly classified into two types –Fixed ResistorsVariable ResistorsFixed ResistorsThe fixed resistor is defined as the resistor whose resistance value does not change with the any change in temperature or voltage. These resistors are available in different shapes and sizes. The main function of an ideal fixed resistance gives a stable resistance in all situations. ... Read More
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A wattmeter is an instrument which is used to measure electric power given to or developed by an electrical circuit. Generally, a wattmeter consists of a current coil and a potential coil.Types of WattmeterElectrodynamometer wattmeter – for both DC and AC power measurementInduction wattmeter – for AC power measurement onlyWorking Principle of Electrodynamometer WattmeterThe electrodynamometer wattmeter works on the dynamometer principle i.e. a mechanical force acts between two current carrying conductors or coils.It consists of a fixed which is divided into two halves which are parallel to each other and is connected in series with the load while the moving ... Read More
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A Unijunction Transistor (UJT) is a three-terminal semiconductor device. The main characteristics of UJT is when it is triggered, the emitter current increases re-generatively until it is limited by emitter power supply. Due to this characteristic feature, it is used in applications like switching pulse generator, saw-tooth wave generator etc.Construction of UJTThe UJT consists of an n-type silicon semiconductor bar with an electrical on each end. The terminals of these connections are called Base terminals (B1 and B2). Near to base B2, a pn-junction is formed between a p-type emitter and the n-type silicon bar. The terminal of this junction ... Read More
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A transistor can be used as a solid state switch. If the transistor is operated in the saturation region then it acts as closed switch and when it is operated in the cut off region then it behaves as an open switch.The transistor operates as a Single Pole Single Throw (SPST) solid state switch. When a zero input signal applied to the base of the transistor, it acts as an open switch. If a positive signal applied at the input terminal then it acts like a closed switch.When the transistor operating as switch, in the cut off region the current ... Read More
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Transistor as an AmplifierA transistor can increase the strength of a weak signal and hence it can be used as an amplifier in a circuit. The weak signal is applied between the emitter – base junction and output is taken across the load connected in the collector circuit.In order to achieve desired amplification, emitter – base junction must remain forward biased. For this, a DC voltage VBB is applied in the input circuit in addition to signal. This DC voltage is known as Bias Voltage and its magnitude is such that it always makes the emitter – base junction forward ... Read More
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An SCR is a three-terminal, three-junction, and four-layer semiconductor device that is used to perform switching functions in power circuits.Sometimes the SCR is also called as Thyristor.Constructional Details of SCRThe SCR has three pn – junctions, and four layer of p and n type semiconductor joined alternatively to get pnpn device. The three terminals are taken – one from outer p – type layer called anode (A), second from the outer n – type layer called cathode (K) and the third from the internal p –type layer called gate (G).Working of SCRIn a SCR, the load is connected in series ... Read More
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Important TermsAC Circuit − A closed path followed by alternating current is called as an AC Circuit.Resistance − The measure of opposition offered by a material in the path of electric current is known as resistance of that material. The element possessing the resistance is known as Resistor.Peak Value of Voltage or Current − It is the maximum value attained by an alternating quantity. It is also called as Amplitude.Average Value − The arithmetical average of all values of an alternating quantity over one cycle is called as average value. For sinusoidal voltage or current, $$\mathrm{I_{avg}=\frac{2I_{m}}{\pi}=0.637I_{m}}$$$$\mathrm{V_{avg}=\frac{2V_{m}}{\pi}=0.637I_{m}}$$Root Mean Square (RMS) value ... Read More