Hi, there. A battery is a power supply, a source of potential difference which drives current. In itself, a battery is not a circuit, but if you attach it to a load (a resistance), then a current will form and a circuit is made!
Parallel
no it doesn't if the door is opened when its ON it makes a circuit and starts the car alarm
They are wired in series.
It is a closed circuit if there is a load in the circuit (light bulb etc), otherwise it is a short circuit (+ to - on a car battery with a screwdriver)
No, the battery is part of it's circuit. In fact nothing in the car will work without the battery.
No, it is not normal for a car battery to spark when connecting it. Sparks can indicate a poor connection or a short circuit, which can be dangerous and should be addressed immediately.
The purpose of the battery in a circuit is to wive energy to the circuit
have the alternator circuit checked
i believe it would short circuit
Because you won't get a complete and closed circuit without a ground.
A fully charged cell in a car battery produces 2.2 volts, there are 6 cells in a battery. That would make true open circuit voltage on a fully charged battery at 13.2 volts. So a 12 volt open circuit reading is a discharged battery. The battery can have enough chemical reaction to produce voltage but not enough potential or power to crank the engine. Think about a fresh 9 volt battery. It is big enough to produce 9 volts, but not enough to crank a car or even light the dome light dimly. A car battery wears out slowly from the time it is purchased. Eventually it doesn't have enough power or amperage left to operate the car.
The bulging is caused by gassing. This is caused by overcharging or by a short circuit inside the battery. The acid inside the battery is turned to gas and it expands the sides of the battery.