Simple sundial making method

The simple method of making a sundial is as follows:

Tools/materials: 1 paper plate, pencil, 1 small plasticine, paper tape, pencil.

1. Divide the back of the circular paper tray into 12 at equal intervals, then write the numbers 1 to 12 respectively, and decorate the paper tray with paper tape.

2. Make a small hole in the middle of the paper tray. After inserting the pencil into the small hole, insert the plasticine at the end of the pencil into the other side of the paper tray and fix the pencil with plasticine.

3. Put the homemade sun clock in a sunny place, and adjust the angle of the paper tray to synchronize it with the real time. Note the shadow of the pencil. At different times, the length of the shadow is obviously different.

The principle of sundial

The name of a sundial consists of two words: "day" and "sundial". The sun means the sun, the sundial means the shadow, and the sundial means the shadow of the sun.

So the so-called sundial is to use the linear propagation of light. During the day, the shadows cast by objects illuminated by the sun are constantly changing. First, the length of the shadow is changing. The shadow is the longest in the morning. As time goes on, the shadow becomes shorter and longer after noon.

The second is that the direction of the shadow is changing, because we are in the northern hemisphere, the shadow in the morning is in the west, the shadow at noon is in the north, and the shadow at night is in the east. In principle, it can be timed according to the length or direction of the shadow, but it is more convenient to time according to the direction of the shadow, so the sundial is usually timed according to the direction of the shadow.