Electricity

Free online electricity lessons for elementary school,  middle school and high school.

 

How to build simple circuits and draw diagrams

Basic electrical circuit including a bulb

1) 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 terminals.

2) 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.

3) 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.

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