What is the main advantage of alternating current over direct current for supplying homes and factories?
AIt carries far more charge per second
BIt needs no wires to travel along
CIt cannot be turned into heat
DTransformers can change its voltage
Answer & Solution
Correct answer: D. Transformers can change its voltage
1. Transformers work on a changing magnetic flux, so they only work with alternating current.
2. That lets the voltage be stepped up to a very high value at the power station.
3. High voltage means low current for the same power, and low current means little energy lost as heat in the lines.
4. The voltage is then stepped down again close to the buildings that use it.
5. Alternating current still needs conductors and it still heats a resistor, which rules out the last two options.
_Source: Siyavula Physical Sciences Grade 12 (Everything Science, CC BY 4.0), Chapter 11: Electrodynamics_