Describe an experiment to show that electricity flows only if the circuit is complete and it does not flow if the circuit is incomplete.

1. Take about 1 metre long insulated metal wire and cut it into two halves by a blade.
2. Remove the plastic covering at the ends of each wire.
3. Take a torch bulb and with help of cello tape fix one end of each wire to each terminal of the bulb.
4. Take a cell.
5. Fix the other ends of the wires to the terminals X and Y of the cell.

We will see the bulb will glow.

Electricity flows from terminal X of the cell to the bulb through wire 1, then through filament of the bulb to wire 2 then to terminal Y of the cell. As the circuit is complete or closed the electricity flows along the circuit and the bulb glows.

Now remove the wire 1 from the bulb connected to terminal X of the cell as shown below.

We will see bulb will not glow.

As wire 1 is removed so circuit is incomplete or open, so electricity does not flow, hence bulb will not glow.

The above experiment show that electricity flows only if the circuit is complete and it does not flow if the circuit is incomplete.