You must plug in most appliances before they will work. where does the energy in an electrical outlet come from

The electrical outlet consists of wires which are coming from a meter box installed in buildings/houses. electricity is produced in power houses either via electromagnetic induction or by using hydro-power, from where the power plant sends electricity to a grid of power lines. the transmission wires then carry electricity to   power substations, where voltage of electricity is reduced so that it can be carried by smaller power lines. overhead and underground power lines in turn carry electricity to transformers, where the voltage of electricity is reduced further to be used safely in homes. thus, electricity at homes is coming from transformers via power lines. when we plug an appliance into an electrical outlet, it completes the circuit, allowing for electricity to flow and appliance to work.

Because its reliable.   there is no pollution  the chances of a radiation leak is low