Mains electricity refers to which description?

• A. Direct current at 50 Hz and 230 V
• B. Alternating current with a frequency of 50 Hz at 230 V that is provided to houses, shops, etc.
• C. Direct current at 110 V
• D. Alternating current at 60 Hz

Answer: (B)

Mains electricity is the alternating current supplied by the power grid to buildings. This means the current changes direction and the voltage varies in a 50 Hz cycle in many regions, with a typical effective (RMS) voltage of about 230 V. That combination—alternating current, 50 Hz, and 230 V—describes the common domestic supply to houses, shops and similar places. It isn’t direct current, and some countries use 60 Hz or different voltages, so the 50 Hz at 230 V description is the one that matches the typical mains supply used for everyday appliances.