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Electricity & Megnetism

Can a transformer operate on DC?

A transformer cannot operate on a steady or unchanging dc voltage such as that of a battery.It requires a voltage which rises and falls.Since an ac voltage not only changes its magnitude but its direction as well,it is used to operate the transformers. However,a transformer will operate from dc voltage if this voltage also undergoes changes.Transformers used for audio amplifiers ...

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Eddy current testing principle

What is eddy current? A current induced in a conductor when subject to a varying magnetic field.Such currents are a source of energy dissipation (eddy current loss) in alternating current machinery.The reaction between the eddy currents in a moving conductor and the magnetic in which it is moving is such as to retard the motion.This property of eddy currents is ...

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Heating effect of electric current

Joule’s law of heating by electric current: “The heat produced in a conductor is: (1) Directly proportion the square of current passing through the conductor,(H ∝ I²) keeping R and t constant; (2) Directly proportion to the resistance of the conductor (H ∝ R) keeping I and t constant;and (3)Directly proportional to the time of flow of current (H ∝ t) keeping I ...

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What are some applications of a step up transformer?of a step down transformer?

Applications of a step up transformer: For Transmission of electric power from power station to consumer,voltage is step up by using step up transformer.It minimizes the power loss in transmission line. Applications of a step down transformer: Step down transformer decrease the voltage to a safe value at the end of the transmission line where the consumer of electric power ...

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Why would power distribution systems be less effective without alternating current?

Most larger power distribution systems are AC.The power is transmitted from power stations at much higher voltage to minimize the power loss.At the end of the line where the consumer is located,the voltage level is reduced to a safe value for domestic use.The crucial factor is that it is much easier to increase and decrease AC voltage than DC,so AC ...

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Hall effect semiconductor

What is the Hall effect? “An effect when occurring when a current carrying conductor is placed in a magnetic field and orientated so that the field is at right angles to the direction of the current.”An electric field is produced in the conductor at right angles to both the current and the magnetic field.The field produced is related to the ...

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Inductance of solenoid and toroid

What is solenoid? Solenoid is defined as:”A long tightly wound cylindrical conducting wire is called solenoid.” Magnetic field due to solenoid: Consider a solenoid having n turns per unit length.When current passes through the solenoid ,magnetic field is produced inside the solenoid which is directed along the axis of solenoid.The magnetic field in space outside the solenoid is so weak ...

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Ampere’s circuital law and its derivation

What is ampere’s law? According to this law “The line integral of magnetic field B along a closed path due to current is equal to the product of the permeability of free space and the current enclosed by the closed path”. Mathematically it is expressed as: Where μ0=permeability of free space i=current flowing through the conductor. Proof: Consider a straight ...

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Electric field and electric field lines

What is electric field? “The electric field is a region around a charge in which it exerts electrostatic force on another charges.” According to coulomb’s law ,if a unit positive charge q0 (call it a test charge) is brought near a charge q (call a field charge) placed in space,the charge q0 will experience a force.The value of this force depends ...

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Kirchhoff’s voltage law definition

What is Kirchhoff’s Voltage Law? Kirchhoff’s voltage law is a fundamental circuit law that states that the algebraic sum of all the voltages around a closed path is zero or, in other words,the sum of the voltage drops equals the total source voltage. In an electric circuit, the voltages across the resistors(voltage drops) always have polarities opposite to the source ...

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