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Electricity produced at a power station is transmitted to the consumer through wires. These wires have resistance R so when the current I flows through these wires for certain time t, the electrical energy is wasted in the form of heat (I2Rt). Power loss during the long distance supply of alternating current can be reduced by either reducing resistance of transmission or by decreasing the magnitude of current flowing in the resistance can be reduced by using very thick wires but it is not economical as the cost of manufacturing and installing such long and thick wires will be very high and to decrease the current flowing in the resistance can be reduced by using long and thick wires. The use of long and thick wires is not economical so transformers are used to decrease the current flowing through the wires.
The electric power generated at the power station is fed to the primary coil of a step-up transformer. Step-up transformer makes the voltage high and low alternating current. This low current at high voltage is carried by the transmission wire to the sub-station which will reduce the power loss. After transmission to the substation, a step-down transformer is used to decrease voltage and increase the alternating current.
The induced circulating currents produced in a metal itself due to change in magnetic flux linked with the metal are called eddy currents.
When a metallic piece is placed in a changing magnetic field, the induced currents are set-up in the metal piece which is eddy currents. The direction of eddy currents is given by Lenz's law.
Reference
Manu Kumar Khatry, Manoj Kumar Thapa etal.Principle of Physics. Kathmandu: Ayam publication PVT LTD, 2010.
S.K. Gautam, J.M. Pradhan. A text Book of Physics. Kathmandu: Surya Publication, 2003.
The induced circulating currents produced in a metal itself due to change in magnetic flux linked with the metal are called eddy currents.
Eddy currents are used for the localized heating of tissues in human body which is called diathermy.
Speedometer is a device used to measure the instantaneous speed of vehicle.
According to Lenz's law, eddy currents always flow in such a direction as to oppose the motion which has produced them.
In order to reduce the speed of train an electromagnet is turned on that applies its field to the wheels.
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