The teachers of Geeta's school took the students on a study trip to a power generating station, located nearly 200km 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 (ac) 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.
Explain with an example , how power loss is reduced if the energy is transmitted over long distances as an alternating current rather than a direct current .

Explanation

At the electric power producing station, a step-up transformer is used to increase the alternating voltage upto several kilovolt. So the electric current flowing through transmission wires decreases . As Joule's heating is proportional to square of current, the loss of electrical energy across transmission wires decreases due to decrease in current.