Question

Electrical energy is transmitted over large distances at high alternating voltages because:

• A. For a given power, there is a lower current, thus less power loss.
• B. For a given power, there is a higher current, thus more efficient transmission.
• C. Transmission lines are better suited to carry high voltage.
• D. The power stations generate power at high voltage and it is convenient to reduce it.

Hint:

Double the voltage, halve the current, and you get one-fourth the power loss!

Answer 1

The Correct Option is A

Step 1: Concept
Power loss in transmission lines is primarily due to Joule heating, calculated as $P_{loss} = I^{2}R$.

Step 2: Relationship between V and I
For a constant power $P = VI$, transmitting at a high voltage $V$ means the current $I$ must be low ($I = P/V$).

Step 3: Reasoning
Since $P_{loss}$ depends on the square of the current ($I^{2}$), reducing the current significantly decreases the energy wasted as heat in the wires.

Step 4: Conclusion
High voltage transmission minimizes power loss by reducing the current. Final Answer: (A)