The game of making a domestic telephone

The necessary materials:

1. Two sets of tin - box.
2. 5 - 10 metre long piece of thread
3. A nail of small size

Presentation of the game:

Make a small hole with the nail through the base of each of the boxes. Enter the thread into the holes and make a knob in each end. Because of the knobs, the thread cannot come out of the boxes. Now, the boxes should be held out by two persons standing at two opposite places and the thread should be extended up straight. One of the friends should set a box by his ear while the other to speak. Similarly, set the box by the ear and ask your friend to say something. In this way, one can talk to his friend over a domestic telephone having it connected from a room to any other or the house of one's friend.

The scientific reason:

As the thread is extended straight, the vibration of sound in the base of the tin box is produced while speaking. This vibration reaches the base of the other box through the thread and there is produced an another vibration which gets spread over the air present in the box and then reaches the ear of the friend who is listening.