- A pen or a pencil
- A piece of paper
- A piece of Thread or string
- A sewing needle (Everything up to this point can be obtained from any convenience store)
- A desk lamp with an adjustable neck or a lamp which can be pointed upwards (Can be obtained from an electronics shop or a hardware shop or a convenience store)
- At first, draw a spiral snake or just a spiral on a piece of paper just like the picture above. Make sure that the snake or the spiral is at least five inches in diameter.
- Cut a piece of string or thread which should be about twelve inches long.
- Now use the needle to pull the needle and thread/string through the snakes eye or the beginning of the spiral.
- Then knot the thread so that you can use it to hold the snake/spiral up.
- Adjust the desk lamp in a way so that the light points upwards.
- Hold the piece of string/thread so that the snake/spiral hangs about three to four inches above the light bulb or the desk lamp. [Warning: Don’t let the snake/spiral touch the bulb directly.]
- Hold your hands as still as possible or tie the string/thread with a stand to hang the snake/spiral above the light bulb of the lamp.
- Now observe what happens.
After a few seconds, the snake/spiral should begin to spin.
The light bulb of the desk lamp not only produces light but also heat. The heat produced by it warms the air surrounding the bulb. When air gets hot then it lightens up. When the air around the light bulb gets heated up it becomes lighter than the room-temperature air. So the air around the light bulb rises away from the light bulb. When the air surrounding the light bulb is gone there is a vacuum in the area then. Cooler air from the surroundings come to fill the vacuum up so that it can be balanced. This way the hot air around the light bulb is actually being replaced by the cooler air. When the cool air fill up the vacuum they also become heated up by the warmth of the light bulb of the desk lamp and rises away from the light bulb. While the light bulb is on, it will produce heat and this phenomena will happen again and again like a circle. Between the hot air rising away and the cooler air coming down, a convection current is created. This causes the snake/spiral to spin.
To put it more simply, every time the hot air rises upwards it pushes the snake/spiral and. The snake/spiral acts like a fan or propeller and starts to spin.
MORE EXPERIMENTS FOR YOU:
- Use a paper fan or a paper propeller instead of a snake or a spiral.
- Can you rotate a small dynamo using the snake/spiral or perhaps paper fan/propeller?