1. A hard plastic pipe with uniform thickness, 3 cm in diameter and 4 cm in length; A soft wooden stick with the thickness of plastic pipe and the length of 5 cm; Two corks; Two thin iron sheets; A sewing needle.
2. Making tools
One hacksaw, one scissors, one awl and one knife.
3. manufacturing steps
① cut the plastic pipe from the middle, divide it into two sections with equal length, and drill a small hole at the top and bottom of each section. Then use a 5 cm long soft wooden stick to connect the two pipes, and use a sewing needle to pass through the middle of the soft wooden stick.
② Cut the thin iron sheet into two brackets and two figures, and fix the figures on both sides of the plastic pipe.
③ Fill the pipe with water and plug it with a cork, put the sewing needle on the bracket, and adjust the balance of the pipe on the bracket. At this time, water flows out rhythmically from the small hole under the tube.
At this time, as long as one end of the seesaw is pressed, the seesaw will automatically tilt up and fall, and the water on both sides will drop out in turn until all the water drops out. Attention, please put it in a basin to prevent the water from wetting the table. Think about why it automatically rises and falls.
Fire alarm
Take a waste starter, remove the aluminum shell, cut off the area capacitor, and gently smash the glass bubble outside the bimetal, so that the bimetal remains on the starter base. Connect the base with the battery, electric bell and small electric bead in series with slender copper wire to form a circuit, as shown in the figure.
Adjust the distance between the moving and static contacts A and B, when the flame lit by a match is close to the metal plate. The light is on and the bell rings.
When in use, use two long copper wires to place the bimetallic strip and its seat in a place where people often move. When the temperature in the place where people are prone to fire rises to near the ignition point, an audible and visual alarm will appear.
/subject/physics/sypt.php There are many more you can look at yourself and find the one that suits you.
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