How to do tricks for children on Halloween: bats and ghosts
Until the date of Halloween - it is celebrated on October 31 - there is not much time left, and it's time to think about how to spend a Halloween evening with children (if such a holiday in your life takes place, of course). Like any other holiday, it can be used not only as a reason to fool around and try on carnival costumes, but also for playing games and activities with children. For example, this evening you can conduct experiments in physics - with ghosts and bats. What kind of tricks you can do to entertain children with your own hands on Halloween, the author of the blog "It's Interesting."
The bat hovers above the candlestick
When you light a candle in a homemade candlestick, hot air rises from it and creates a powerful stream. In this stream, a paper figure suspended above a can-candlestick on a thread begins to fly over the flame and flutter from its vibrations. The experience is simple, but it fascinates the children - the figure seems alive!
You will need:
- tablet candle
- glass half liter jar
- paints (better to take acrylic, but gouache is also suitable)
- First we make a candlestick. We designed it in the form of a pumpkin in the image of Jack. To do this, paint the can and wait for it to dry completely.
- We wrap the neck of the can with wire, leaving one end of it long (10-15 centimeters). Bend the long end as shown in the photo. At the very end we make hooks - we will tie a thread for it.
- Cut out a small bat paper figure.
- Cut a thread about 10 cm long. At one end we tie a knot and thread it through the center of the paper figure. The second end of the thread is tied to the end of the wire. The total length of the thread, from which the figure hangs down, after all the tying-binding, we have about 5 cm left - this is quite enough for the figure to fly in convective hot air from the candle.
- It remains only to put a candle in the jar and light it - and you can conduct an experiment!
The meaning of the experience. The air, heated by the flame of a candle, expands, its density decreases, and according to Archimedes' law, it begins to rise. And the cold air that is nearby, rushes to his place. There he also heats up and everything repeats again. This is how the convective flows are formed, in which the paper figure hovers.
Announce to the children that now you will make paper ghosts that can dance. And children will be able to see this with their own eyes!
You will need:
- A4 sheet of office paper
- central heating battery (or any other heat source - heater, stove or candle)
- Draw on paper a circle of maximum diameter. And inside it, draw a spiral (it doesn’t have to be even, it’s enough to draw it by hand). At the end of the spiral, draw the head of the ghost, decorate it - draw the eyes, mouth.
- The head can be made both in the center of the spiral and outside - let the children try both options and choose the one that is most effective. After that, the circle should be cut and cut in a spiral. And finally, it remains to make a small hole in the ghost's head and attach a thread to it.
- Now you need to hang the resulting figure for the string above the heat source - and it will begin to rotate by itself. Pay attention to the children that if you just unwound the spiral, then after a while it would stop spinning. But our ghost without stopping dancing day and night!
- Experiment with different sources of heat and distance to them. We had the most spectacular option when we held a ghost over the gas stove. (Just do not forget about safety!)
Sense of experience - the phenomenon of convection, as in the past experiment. It consists in the fact that the lower, more heated layers of the substance spontaneously (that is, without any assistance) rise upwards, and the cold substance descends. Below it heats up again and flies up again - this is how the circulation of the substance is carried out.
In our case, the air from the battery or the flame heats up and rises. Its streams, flowing around the spiral, make it rotate. And then this air at the ceiling cools down, goes down, and the process repeats again and again. Therefore, our ghost never stops, and all the time spinning in his dance.
Where else can we see convection? For example, the fact that smoke rises from a chimney up is also a convection. It is because of it there is a thrust that ensures any burning. And also - the formation of clouds. Night-day winds (breezes) by the sea.
Here are how many phenomena - and they all come from the same thing that makes our little paper ghost dance.
Everyone knows that according to national signs, vampires, werewolves and so on do not cast a shadow. How can it be that something does not have a shadow? We set up a very simple experiment with children.
In a dark room, take a candle, light it and look at its shadow on the wall (for this you need a second source of light: a desk lamp or a flashlight). There is a shadow from the hand, there is a shadow from the candle, there is a shadow from the wick - but there is no shadow from the flame! Like a vampire!
Fearfully? Not at all! After all, the shadows are obtained when the rays of light can not pass through the barrier. Solid bodies for light are such an obstacle. But the fire - no. After all, the light of a lamp, and the light of fire, and the light of the sun are radiation. And all these types of radiation from different sources only add up, completely without interfering with each other to go their own way.