29. Household ac supply provides 250 V at 50 Hz. Name and give specification of the
device you will use to run an electrical machine which needs (1) 25000 V, (11) 25 V for
its operation. Draw the symbol of the device in each case showing how supply and
machine are connected. In which of these two cases, will the machine draw more
current than the supply ? Give reason for your answer. Will the machine run if the
supply were dc ?
Answers
Answer:The rate at which alternating current reverses direction is called its frequency, expressed in hertz. Thus, standard household current in India is 50 Hz. AC electricity alternates back-and-forth in direction 50 times per second, according to the electrical system in the country.
The electric power line enters our house through three wires- namely the live wire, the neutral wire and the earth wire. To avoid confusion we follow a colour code for insulating these wires. The red wire is the live wire, and the black wire is neutral. The earth wire is given green plastic insulation.
The live wire has a high potential of 220 volts whereas the neutral wire has zero potential. Thus the potential difference between the live wire and the neutral wire is 220-0 = 220 volts.
Hence, voltage and frequency is the a.c. supplied to our houses are 220 V and 50 hz respectively.
Explanation: