Today, most of the electrical devices we use require ac voltage. This is mainly because most of the electrical energy sold by power companies is transmitted and distributed as alternating current. Why is ac voltage preferred over dc voltage?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Both (1) and (2)
Option (1) It is economical — Incorrect. The statement is true, because ac energy can be sent economically over long distances. But it is only one of the two reasons, so this option alone is incomplete.
Option (2) It can be easily stepped up or stepped down — Incorrect. This is also true, as transformers change ac voltages easily. Taken alone, though, it leaves out the other reason.
Option (3) Both (1) and (2) — Correct. Both statements hold:
Ac voltages can be easily and efficiently converted from one voltage to another by transformers, so (2) holds.
For long-distance transmission the voltage is stepped up. This keeps the current and the \( I^{2}R \) loss in the lines small. So the energy is transmitted economically, and (1) holds.
NCERT (2026-27):
Introduction – “… The main reason for preferring use of ac voltage over dc voltage is that ac voltages can be easily and efficiently converted from one voltage to the other by means of transformers. Further, electrical energy can also be transmitted economically over long distances.”