What I mean is how is there still enough electricity when three or four items are plugged into the same socket. You'd need to use more batteries for more items for example.
it work on a load principle you have to have enough power to run whats needed or it wont work like a amp or a cap
Look at the wire coming into the house fuse box. That determines how much electricity by amperes. Old houses have 100 amp and new 200 amp available due to the increase in electrical appliances we have today. From the fuse box it is branched out like piping for water. So, conventionally, each branch circuit can supply 20 amps of power. You plug in a lamp with a 100 watt bulb and that takes 1 amp. 19 amps left, plug in a toaster which uses 15 amps and you'd have 3 amps left and if you plugged in something that took 4 amps., the circuit breaker would trip or fuse blow. That's the general idea but there is alot more to wireing than that. Hope that helped.
I think you are asking for sockets in house wiring.Connections from any particular outlet depends upon two things- Capacity of source and capacity of feeding circuit.In this case source is very much bigger as houses are connected to grid of capacity in thousands of megawatts through various transformers ,su source will not be any problem. Another is the feeder capacity.The sockets are connected to the incoming power source through copper / aluminium wiring of various sizes.It is the size of wire which decides how much load can be connected to a particular socket. As you has mentioned batteries...in case there is limited source in form of battery, the load will depend upon Ampere hour capacity of battery. A 100Ah source can feed 10 A load for 10 hours.
Because there is usually much more than enough power,(voltage) coming into the socket to carry the load of the items being plugged in. A circuit can carry as much as 12-15 small loads before the breaker trips.
There is enough electricity 'behind' the socket to power 3 or 4 appliances.
The mains to your house comes down 1 wire and to your consumer unit.There there are several cables that distribute the power around your house. Typically between the incoming cable and the next cable there is a circuit breaker. Each appliance takes a certain amount of current and solong as the total current of all of them is less than the circuit breaker then there is power to run the appliances.
Overall your house would be allowed to use 100 amps of current.
Batteries will power several things all at once, however they only have so much energy in them. Once the energy is used up then they wont work any more - and addinig more things to the batteries means that the power is used more quickly. In a plug, the energy comes straight from the power station and so unless there is a big problem there will be enough energy for all the appliances you want to use