Question

Which of the following statements is not true for electric energy in ac form compared to that in dc form?

• A. Production of ac is economical.
• B. ac can be easily and efficiently converted from one voltage to the other.
• C. ac can be transmitted economically over long distances.
• D. ac is less dangerous.

Hint:

AC peak voltage is \(\sqrt{2} \times V_{rms}\). For a 220V supply, the peak is actually 311V, which is one reason why it's more hazardous than 220V DC.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Alternating Current (AC) and Direct Current (DC) have different physical properties and industrial advantages. This question asks to identify a \textit{false} statement about AC.

Step 2: Detailed Explanation:
1. Statement A: True. AC generators are simpler and more robust than DC generators. 2. Statement B: True. Transformers allow us to step-up or step-down AC voltage with very high efficiency. 3. Statement C: True. Because we can step-up AC to very high voltages, we can transmit it at low current, reducing \(I^2R\) heat losses. 4. Statement D: False. AC is generally considered \textit{more} dangerous than DC of the same voltage. AC of 220V has a peak value of about 311V. Furthermore, AC frequencies (50-60Hz) are particularly disruptive to the human heart's rhythm.

Step 3: Final Answer:
The statement "ac is less dangerous" is not true.