Question

The teacher of Geeta’s school took the students on a study trip to a power generating station, located nearly $200\,Km$ away from the city. The teacher explained that electrical energy is transmitted over such a long distance to their city, in the form of alternating current raised to a high voltage. At the receiving end in the city, the voltage is reduced to operate the devices. As a result, the power loss is reduced. Geeta listened to the teacher and asked questions about how the ac is converted to a higher or lower voltage.
(a) Name the device used to change the alternating voltage to a higher or lower value. State one cause for power dissipation in this device.
(b) Explain with an example, how power loss is reduced if the energy is transmitted over long distance as an alternating current rather than a direct current.
(c) Write two values each sown by the teachers and Geeta.

Answer 1

Hint: The current from the power station transports to all the remote parts of the villages by the wires in the form of the alternating current. The alternating current wave moves above and below the axis whereas the direct current moves only above the axis.

Complete step by step solution:
(a) Transformer is the device that helps to change the alternating voltage from the power station to either high or low value. The power dissipation in the transformer device mainly occurs due to the losses in the eddy current.

(b) When compared to the direct current, alternating current is used to transmit over very long distances. The losses in the transmission can be avoided by using the high voltage but low current through the transformer. In the alternating current, the peak voltage is appeared for only the fraction, there will be zero voltage twice during each cycle of the wave. Hence it has less wastage of power when compared to direct current.

(c) The values shown by the teacher are sharing knowledge to others, caring for the students, concerned. Where the values of the students are keen listeners, good learner, inquisitive etc.

Note: The voltage step and down is possible only in the alternating current since it can move in bidirectional. But it is not possible in direct current. From the power station, the ac current moves to the transformer at high voltage and from there it moves to the homes at lower voltage.