Electronics & Electrical Articles - Page 42 of 56

A device that can measure the resistance directly is known as an ohmmeter. There are two types of ohmmeters asSeries Types OhmmeterShunt Type OhmmeterSeries Type OhmmeterCircuit DiagramThe circuit of a series type ohmmeter consists of a D’Arsonval galvanometer (PMMC meter) connected in series with a resistance and a battery. It has two terminals (A and B) to which the unknown resistance (Rx) is connected.Since the meter and unknown are in series, the current through the meter depends upon the value of unknown resistor. The meter indication is directly proportional to the value of unknown resistor, provided that calibration problems are ... Read More

When the two coils are arranged in such a way that a change of current in one coil causes an emf to be induced in the other, the coils are said to have mutual inductance. The mutual inductance is denoted letter M and measured in Henry.Consider two coils, coil 1 and coil 2 placed adjacent to each other. When a current I1 flows in the coil 1, a magnetic flux (Φ1) is produced in it and some part of the Φ1 links with the coil 2 and is known as mutual flux (Φm).Now, if the current in the coil 1 changes, ... Read More

The Magnetomotive force (MMF) is defined as the work done in moving a unit magnetic pole once around the magnetic circuit. It is a magnetic pressure that tends to set up magnetic flux in a magnetic circuit. Mathematically, the mmf is the product of current and number of turns of a coil.Consider the coil consisting of N turns and an electric current of I amperes flowing in it. Therefore, the mmf is given by, Magnetomotive force, MMF = 𝑁𝐼 … (1)Unit of MMFSince MMF is a product of current in amperes (A) and number of turns (T) in a coil, ... Read More

The magnetic field intensity is the force acting on a unit test north-pole (i.e., N-pole of 1 Wb) placed at a point in the magnetic field. It is denoted by H.The magnetic field intensity is a vector quantity, possessing both magnitude and direction.The magnetic field intensity is also known by different names like Magnetising Force, Magnetic Field Strength, and Magnetic Potential Gradient etc.ExplanationConsider a point x situated at a distance r meters from a pole of m Wb. Let a unit north-pole (i.e., a pole of 1 Wb) is placed at point x.Hence, by the definition, the magnetic field intensity at ... Read More

Distribution SystemThe distribution system is defined as the part of electrical power system which distributes electrical power for local use. On the basis of voltage level a distribution system can be classified in two categories viz.Low Voltage (LV) Distribution SystemHigh Voltage (HV) Distribution SystemLow Voltage (LV) Distribution SystemThe distribution system which operates on the voltage levels that are directly utilised without any further reduction. It is also known as low tension (LT) distribution system or secondary distribution system. The low voltage distribution system is the part of electrical power distribution network which carries electrical power from distribution transformer to energy ... Read More

Single Phase SystemInstantaneous PowerThe instantaneous power in an AC circuit is defined as the product of instantaneous voltage (v) across the element and instantaneous current (i) through the element and is denoted by lower case letter p.Instantaneous Power, $\mathrm{p=v\times\:i}$Since, the values of instantaneous voltage and instantaneous current changes from instant to instant, thus the instantaneous power changes with time. The instantaneous power (p) is measured in watts. The instantaneous power may be positive or negative. A positive instantaneous power means power flows from source to load whereas negative instantaneous power means power flows from load to source.Instantaneous Power FormulaCase 1 – ... Read More

The magnetic flux density is the measure of amount of magnetic flux in each square meter of the magnetic field. Therefore, the magnetic flux density is defined as the magnetic flux passing normally (at 90°) per unit area and is denoted by B, i.e., Magnetic flux density, $$B=\frac{\phi}{A}$$Where, Φ is the magnetic flux, A is area normal (or perpendicular) to flux.The magnetic flux density is a vector quantity i.e. it possesses both magnitude and direction.Unit of Magnetic Flux DensityAs we know, the magnetic flux density is$$B=\frac{\phi}{A}=\frac{Weber}{meter^{2}}=Wb/m^{2}=Tesla(T)$$Therefore, the magnetic flux density is measured 𝑊𝑏/𝑚2 or Tesla (T), named in honour of Nikola ... Read More

Capacitance - DefinitionThe ability of a capacitor to store charge is known as its capacitance. In other word, the capacitance can also be defined as the property of a material by virtue of it opposes the any change in voltage applied across it.Capacitance: FormulaExperimentally, it has been found that, the charge Q stored in a capacitor is directly proportional to the voltage across it, i.e.$$Q\propto\:V$$$$Q=CV$$Where, C is a constant and is called as capacitance of the capacitor.$$\Rightarrow\:C=\frac{Q}{V}$$Thus, the capacitance (C) of a capacitor can also be defined as the ratio of the charge on the either plate to the voltage ... Read More

Electromechanical RelayAn electromechanical relay is a type of relay which function using a magnetic field produced by an electromagnetic coil when a control signal is applied to it. It is called as electromechanical since it has moving contacts in the output circuit which are operated by applying an electrical signal.Electromechanical Relay: Working PrincipleAn electromechanical relay transfers signals between its contacts through a mechanical movement. It has three sections viz. input section, control section and output section.The input section consists of input terminals where a small control signal is to be applied. The control section has an electromagnetic coil which gets energised ... Read More

Electricity tariff is defined as the rate at which electrical energy is supplied to a consumer.Types of Tariff in ElectricityThe commonly used electricity tariffs are as follows −Simple Tariff – When there is a fixed rate per unit of energy consumed, it is known as simple tariff or uniform rate tariff. In case of simple tariff, the price charged per unit is constant i.e. it does not change with increase or decrease in number of units consumed.Flat Rate Tariff – When different types of consumers are charged at different uniform per unit rates, it is known as flat rate tariff. In ... Read More