How to make Franklin's bells

The bells of Franklin is an experiment designed by Ben Franklin to demonstrate the presence of electrostatic charges in the environment. Below, we will describe how to make Franklin's bells in a simple and easy-to-do experiment.

Franklin Bells


- Two cans of soda.

- A pencil.

- Thread.

- Aluminium foil.

- Cable.

- Adhesive tape.

- One TV.

Assembly procedure

To begin, we will cut out a piece of aluminium foil about 30×20 cm and tape it to the TV screen.

Now, we take about 25 cm of cable and with the help of a pair of pliers we remove about one centimetre of the insulation from the cable at one end, we should see the copper wire free. We fix this end, with the help of the adhesive tape, to the piece of aluminium foil on the TV screen.

Next, in one of the soda cans, we find a place where there is no paint on it (on the unpainted aluminium) and fix the other end of the cable, which we have previously freed of approximately one centimetre of its insulation.

Then, with another piece of wire we connect the other can to ground, thus obtaining the two bells, and we place them on the TV at a distance of about 5 cm from each other.

Sketch of the franklin bells

With one of the sheets from one of the cans and a bit of thread, we make a kind of pendulum that we attach to a pencil. We place this pendulum on top of the soda cans.

Now, we turn on the TV and we can listen to the sound of the bells of Franklin.

How they work

When the TV is switched on, it is charged with static electricity, and through the wires the cans are also charged. One of them attracts the pendulum because they have different charges, the pendulum touches the can and becomes charged like it, and because they have the same charge, they repel each other and the pendulum shoots towards the other can and the process is repeated.

In this way, we can witness the static electricity of the environment, in our specific case, aided by the charge of the TV and the bells of Franklin.

3 thoughts on “Cómo hacer las campanas de Franklin”

  1. DelimAr IbArra

    the cable should be thick or thin...?? the TV should always be on or it turns off and on?

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