(a) The device used to change the alternating voltage to a higher or lower value is step up and step down transformer. In a transformer, we use two coils one is called the primary coil and other is called secondary coil. We know the relation for transformer
E1/E2=N1/N2
where E1 and N1 are voltage and number of turns in the primary coil and E2 and N2 are voltage and number of turns in the secondary coil. The one cause of power dissipation in the transformer is due to heat loss by the eddy current.
(b) When electrical energy is transmitted over a long distance as an alternating current then power loss occurs due to the heat produced by the a.c. current.
Therefore, to reduce the power loss by heat, we reduced the current by increasing the ac voltage with the help of step-up transformer and at the end again sufficient A.C. current is received by converting high voltage to low voltage current with step down transformer as
But in direct current (dc) we cannot use the step up or step down transformer, therefore, Power loss cannot be reduced.
(c) Polite and thankful to each other.