Question

How can you identify the positive terminal of a cell or a battery concealed in a box with the help of a potato?

Answer 1

The principle which we can use here is basically one of the chemical effects of electric current.

• Take one half of potato and insert the copper wires of the circuit connected to two ends of the battery in it as shown in the circuit below.
• Potato contains a small amount of liquid which can conduct electricity.
• When current starts flowing in the circuit, after some time, a greenish-blue spot develops on the potato around the wire which is connected to the positive terminal of the battery.

This way, we can identify the positive terminal of the battery by seeing the coloured spot.