Lighting a bulb using only a flat battery
A bulb can be lit if it is traversed by the electric current produced
by the battery.
There are two possibilities:
A bulb can be lit if its two terminals are in contact with battery's
Lighting a bulb without direct contact with a flat battery
If the bulb can not receive electric current through direct contact, it
can be transmitted through connection wires.
The connection between connection wires and the flat battery requires
alligator clips. Furthermore the bulb must be placed on a support.
In a circuit, the current can be transmitted to the different
electrical components through the connection wires.
Using a switch for controlling the lighting of a bulb
For controlling the lighting of a bulb, that is to say being able to to
decide its functioning, we add a switch.
The switch is inserted on the path of electric current in order to
interrupt it or allow its circulation.
When the bulb shines it indicates that the switch allows current to
flow: The current then follows a path corresponding to a closed loop
and for this reason we say that the switch and the circuit are closed.
If the lamp doesn't shine it indicates that the switch interrupts the
current flow: The switch opens the loop formed by electrical components
and for this reason we say that the switch and the circuit are open.