Electrical power exists in two forms, the AC, and the DC in this section, you'll learn the basics of both.

Electrical cells, batteries, mobile chargers and laptop chargers all provide the dc power. This is the power whose polarity always remains same.

The power coming to our home outlets is the dc power. This power alternates its direction after every 1/50second or 1/60th second.

### Important terms which you should know before proceeding

Voltage level: It is the magnitude of voltage. Your mobile phone has a magnitude of 5 VAC. Whereas the wall outlet at our homes is at 220 VAC.

Stepping of voltages: The process of changing the voltage from one level to another. For example from 220 V to 1000 V.

Transformer: The electrical device which steps voltage levels.

Step up transformer: The transformer which raises lower voltage levels to higher.

Step down transformer: The transformer which decreases voltage levels to smaller levels.

Power generation: The process of generating electricity.

Power transmission: The process of transmitting electricity from the power station to homes.

Transmission losses: The losses which occur during power transmission.

### How electricity is generated and transmitted

Electricity is generated at dams and power stations. A power station takes mechanical input from an external source and utilizes it for rotating the turbine. The turbine itself is synchronized with a generator which converts the mechanical power to electrical power. All types of alternators generate ac electricity whose voltage level ranges between 11 kV-25 kV.

Electricity is generated for us (The consumers). So, we require power transmission from stations to our homes. Electrical power stations are located far away from the populations. Transmission losses are directly proportional to distance. However, we can reduce these losses by stepping up the voltages by using the transformers. So, power is stepped up between 265-765 kV voltage level.

At our homes we require a voltage level of 110/220 V. Near population again step down transformers are installed which decrease the voltage to lower levels.

The stepping of voltages can only be carried by using AC power. So at generation and transmission, we are restricted to use AC.

### How Power is Used

Large appliances including washing machines, fans, air conditioners, coolers, tube lights and geezers require the ac power supply. We directly our ac outlets to power them.

Small circuit components such as resistors, transistors and IC's are built inside our electronic gadgets. Such components require dc power for their operation. All electronic component contains some sort of adapter or charger which takes ac power from outlets and converts it to dc.