1. We know that we usually find some old batteries in our drawers, but we don’t know whether they still have power. It is very troublesome to put in electrical appliances to check and there is no way to know the remaining power. So, you can make a little electroscope.
The method is simple: use a small light bulb, a very small one (like the one on a pendant or toy lamp, available in hardware stores). Then use two thin enameled wires to connect them to the lights respectively. The other ends of the two wires are used to connect the positive and negative terminals of the battery you want to test. According to the brightness of the small light bulb, you can judge the battery power.
2. Take a broken umbrella, remove the cloth, take a wire, connect one end to the TV or radio, and the other end to the umbrella, it will be a good signal receiver. If you want to be more professional, just wrap a few more turns of wire on the umbrella. This is the cheapest, fastest way, and just a little funny.
3 Put a match and a large sewing needle together, wrap them tightly with cigarette aluminum foil, and then bend the aluminum foil at the end with the match head to seal it. Twist tightly. Then install a directional tail fin near the tail, pull out the needle, and it becomes a very simple recoil rocket.
During the experiment, place the small rocket on the wire stand, light a match, and heat it at the part of the aluminum foil tube with the match head. When the temperature rises to the ignition point of the match head, the match box in the foil is ignited, causing the surrounding air to expand rapidly, and the gas is ejected from the tail port at high speed. Due to the recoil effect, the rocket launcher flew forward from the stand.
If you wrap two matches placed end-to-end in aluminum foil, both ends will not be closed. Place it on and heat from the middle. When the match in the cylinder is ignited, the gas spurts out from both ends, and the aluminum foil cylinder still stays on the stand, thus illustrating the conservation of momentum of the system.
4 Rivet two identical protractors at the center of the circle and make them flexible. Rotate and make a gap of l cm in length along the right end of the protractor above. When measuring the angle, let its opening coincide with the two sides of the angle to be measured. The scale indicated by the gap is the degree of the angle; when drawing the angle, First align the gap with the specified scale, and then draw two rays along the opening to complete. This kind of protractor can also measure the angle of three-dimensional objects (such as nuts).
Because this protractor looks like scissors when used, we call it a "scissor protractor".
5
Let me recommend to you the small productions of my classmates back then.
What he made is a small electronic balance model. Note that this is a model and can only weigh very light objects, such as two small scraps of paper. The materials required for production are: a piece of wood (preferably thin, not too big), a washer, paper clip, awl, soldering iron, a few wires, two light-emitting diodes, and a battery. These materials are easy to find. If you don’t have light-emitting diodes, you can go to the electronics market and buy them very cheaply.
The production process is as follows: use an awl to turn a small hole in the middle of the wooden board, bend a paper clip into a hook shape, and fix it on the wooden board through the small hole perpendicular to the wooden board. The hook can catch the washer. Can. Then take two paper clips and straighten half of them, leaving only one bend. In fact, the straightened part is the arm of the balance, and the remaining bent part is the tray. Do the same with the other paper clip. Then weld the two paper clips and the washer together, with the washer in the middle and the paper clips in a straight line. Then hang the washer on the hook and adjust the distance between the hook and the board to about 3mm. Then fix two paper clips under the two trays, and prepare LEDs as indicator lights next to the paper clips. With a circuit set up under the board, the balance acts like a single-pole double-throw switch. This circuit is equivalent to two loops, using only one power supply and two light-emitting diodes. As long as the left side sinks, the left tray will be connected to the pin below it, so that the circuit is connected and the diode lights up; if the weight on both sides is equal, the circuit is blocked and both diodes do not light up.
Added some more, hope you are satisfied!
Finally, I wish you success and a happy mood!
1. Little Balance
Warm reminder: It must be done with the help of parents!
1. First cut the plywood into A, B, C and D.
2. Open at the bottom of B. The middle opening of C and D.
3. Insert the three thin strips as shown in the picture.
4. Nail A to the middle and upper section of B, but be careful not to nail it to death and to allow it to move freely.
5. Cut out a crescent-shaped target board from plywood and mark it with scales.
6. Cut another small strip and fix it on A with all-purpose glue, as shown in the picture.
7. Cut two circular pieces of equal size.
8. Poke four small holes on each side.
9. Cut a small slot on each side of A.
10. Tie the disc with a thin wire and the balance is ready.
Then you can use your own imagination to decorate the small scale. After the experiment, you can also use it as a small ornament. It really kills two birds with one stone
Second, the actor walks on the tightrope
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Actors always hold a long stick when performing on the tightrope. Maybe people will think, doesn't this increase the burden on the actors? After you complete the following experiment, you will change this view.
1. Materials
A piece of white cardboard, a piece of 10 cm long iron wire, a thumbtack, a ball of plasticine, a piece of thin iron sheet 30 cm long and 2 cm wide, tape, Glue, scissors, ruler, etc.
2. Production
1. Use cardboard to cut out the shape of a little person, draw the facial features, paint it with colors, stick a support strip on the back, and fold the feet of the little person forward. , fold the support strip back, stick a thumbtack with glue, cut off the excess, and fold the tip of the thumbtack back.
2. Straighten the iron wire, use plasticine to pinch two small balls of the same size, fix them at both ends of the iron wire, and then use tape to stick the middle part of the iron wire to the "hands" of the villain. People can stand.
3. Place a ruler vertically against the center paper of the iron sheet, fold the iron sheet into a right angle, place it diagonally on the table with the corner facing downwards, secure it with tape, place the figure upright, and align the nail hook with the groove. Ditch, the villain can slowly slide down from the top while remaining smooth.
3. Revealing the secret
Objects are subject to the gravity of the earth. The balance of an object depends on the position of its center of gravity. The lower the center of gravity, the more stable the object. The long and drooping stick can lower the center of gravity. The added weight also helps with balance, so the actor holds a stick when walking the tightrope.
3. Making a hot-air balloon (Kongming Lantern)
Let’s make a hot-air balloon through the hot air of a hair dryer, which can make it rise slowly, just like a real hot-air balloon.
1. First, we cut out 6 to 8 leaf-shaped pieces of paper from soft paper.
2. Fold them in half and glue their edges together to make a balloon.
3. Use tape to stick the four connecting wires to the bottom of the balloon. Use plasticine to secure the other end of the string to the table.
4. Try to adjust the speed of the hair dryer as slowly as possible. Aim the blower upwards at the bottom opening and turn on the switch. The balloon will slowly grow larger, tighten the string, and lift off the table.
You can make a turtle that can sweep the floor. Do you have a shoe brush? Grind off the handle of the shoe brush, press the driver's motor on it, and then stick a cake plate on it for some decoration. , start the motor, and the little turtle is gone!
Prepare the materials and tools for making a sand table: chassis, track, paint, grass powder, turf, silicone gun, waste newspaper, white glue, gypsum, etc.
As needed, you can design the shape and height of the track yourself and use hot silicone to glue it together. (Note: it must be firmly glued and cannot be loose or tilted)
Add textured paper to the track to prevent debris from entering during the production process and should not be removed. Use scrap newspapers to shape the pre-designed shape, which can be fixed with textured paper, then covered with a plaster bandage and sprayed with clean water.
After the basic shape is fixed, plaster is poured on it, which will make the entire shape stronger and easier to paint. (Note: Be careful to avoid the tracks when pouring plaster)
Adhere the building to the already made shape.
When it comes to coloring, pay attention to painting the dark colors first, then the middle colors, and finally the highlights to create a weathered effect, and then plant vegetation.
After planting vegetation and sprinkling grass powder, the making of a simple sand table is basically completed. Finally, don’t forget to hit the track with sandpaper, and you are done
Make a Kongming lantern!
It can fly by itself!
2.1 Material selection and production
① Take a large and extremely thin plastic handbag and cut the handle flat.
②Take a thin copper wire about 60cm long (you can use a copper wire from multiple strands of soft copper wire), and tie the two ends to both sides of the opening of the convenience bag.
③ Wrap an appropriate amount of cotton in the middle of the thin copper wire, and a simple Kongming lantern is made. As shown in the picture.
2.2 Release
Choose a place with no wind (indoors is also acceptable), hold the two corners of the bottom of the convenience bag with both hands, so that the opening faces downward, and make the cotton-wrapped bag The thin copper wire hangs down naturally. Then pour an appropriate amount of alcohol on the cotton, ignite the alcohol, and after a few dozen seconds, the Kongming Lantern will rise into the sky.
2.3 Notes
① The alcohol cotton should not be too heavy. Generally, the total mass (total mass of convenience bag, thin copper wire, and alcohol cotton) can be less than 5g and it is easier to take off.
② The length of the thin copper wire should be appropriate so that the plastic bag will not melt after the alcohol is burned, and care should be taken to prevent fire.
③If you want to pull it down, you can tie another thin copper wire in the middle of the thin copper wire to let it hang down
Actors always hold a long piece of wire during tightrope performances. of sticks. Maybe people will think, doesn't this increase the burden on the actors? After you complete the following experiment, you will change this view.
1. Materials
A piece of white cardboard, a piece of 10 cm long iron wire, a thumbtack, a ball of plasticine, a piece of thin iron sheet 30 cm long and 2 cm wide, tape, Glue, scissors, ruler, etc.
2. Production
1. Use cardboard to cut out the shape of a little person, draw the facial features, paint it with colors, stick a support strip on the back, and fold the feet of the little person forward. , fold the support strip back, stick a thumbtack with glue, cut off the excess, and fold the tip of the thumbtack back.
2. Straighten the iron wire, use plasticine to pinch two small balls of the same size, fix them at both ends of the iron wire, and then use tape to stick the middle part of the iron wire to the "hands" of the villain. People can stand.
3. Place a ruler vertically against the center paper of the iron sheet, fold the iron sheet into a right angle, place it diagonally on the table with the corner facing downwards, secure it with tape, place the figure upright, and align the nail hook with the groove. Ditch, the villain can slowly slide down from the top while remaining smooth.
3. Revealing the secret
Objects are subject to the gravity of the earth. The balance of an object depends on the position of its center of gravity. The lower the center of gravity, the more stable the object. The long and drooping stick can lower the center of gravity. The increase in weight is also beneficial to balance. Therefore, actors should hold a stick when walking on the tightrope
Make a pinhole camera
Method:
Pinhole camera
A pinhole imager can be made based on the principle of pinhole imaging. Clear images can be seen on the screen. If a photosensitive film is installed on the screen, clear photos can also be taken. , this becomes a pinhole camera; but this requires a "shutter" and a slot to hold the film. In addition, the sealing requirements are more stringent than those for ordinary small hole imagers.
The structure of the pinhole camera is shown in Figure 10.6-l. The body is entirely made of horse manure paper and is divided into two parts: a front cover and a rear cover.
Production method
Draw on the horse dung according to the dimensions of Figure 10.6-2, 10.6-3, 10.6-4 (δ is the thickness of the horse dung paper) On the paper, cut along the solid lines of each picture, and then use a knife to gently carve along the dotted lines, but do not carve through, so that a straight edge can be formed when bending. Then paint both sides of each piece black.
Fold the cut outer layer of the front cover (Figure 10.6-2) at 90° along the dotted lines to form a five-sided paper box (the small tongue is glued to the outside of the box). Stick the tape on. Then stick a piece of 120 film black backing paper on the side with the round hole, and use a needle to poke a small hole in the backing paper in the center of the hole, with a diameter of about 0.4 mm (a No. 12 sewing needle has a diameter of about 0.4 mm) ). As shown in Figure 10.6-1, a paper slot is posted on the side of the small hole, and a cardboard strip is inserted into the paper slot, which can not only act as a shutter, but also keep the small hole clean.
Bend the cut inner layer of the front cover (Figure 10.6-3) at 90° along the dotted lines to form a square tube, and glue the interface (the uvula is glued on inside the square tube). Then fold the trapezoidal tongues at the end with the gap into a paper frame, and align the reinforcement frame (Figure 10.6-4) with the gap and glue them together. Cut a paper frame out of cardboard according to the size of the reinforcement frame, align the notches and attach it to the reinforcement frame, and use tape strips to stick the paper frame to the square tube on the outside. A paper frame is formed between the reinforcement frame and the cardboard frame. slot, the film can be loaded or taken out from the side with the notch. The notch is designed for the convenience of loading and unloading the film. After the inner layer is completed, it should be glued together with the outer layer. That is, bend each trapezoidal tongue at the other end of the square tube 90° along the dotted line, apply glue, align the gaps, and insert the outer layer while inserting the inner and outer layers on each side. Insert a piece of horse manure paper in between to ensure that the gap between the inner and outer layers on each side is the same. After the front end of the inner layer is firmly adhered to the side with the round hole on the outer layer, pull out the inserted piece of horse manure paper and the front cover is ready. .
As for the production of the rear cover, except that the side width is 80＋26 mm and there are no holes on the bottom, the rest are the same as the production of the outer layer of the front cover. Refer to the expansion diagram of the outer layer of the front cover and the corresponding dimensions for cutting. Just make it.
How to use
1. The image distance of the pinhole camera is about 64 mm and the light transmission aperture is 0.4 mm, so the aperture is also fixed. Experiments show that the aperture number is about 160. When the brightness of the scene being photographed is different, the exposure time can only be used to adjust it. Since the aperture number of a general camera is about 22, the exposure time of an aperture of 160 cannot be found, so it can be determined according to the ratio of the exposure time equal to the square of the aperture ratio (i.e. t1:t2=(F1:F2)2). For example, when photographing a certain scene, the exposure time is 1/30 second with aperture 16, then the exposure time should be 3.3 seconds with a pinhole camera with aperture 160. The optimal exposure time should also be determined experimentally.
2. The framing method when taking photos with a pinhole camera is shown in Figure 10.6-5. Put one eye close to the midpoint of one side and "aim" towards the two endpoints of the opposite side. Then, the part caught in this angle is the scope of ingestion. Moving the distance between the camera and the scene being photographed can change the size of the image.
3. Exposure: Pick the scene to be photographed, calculate the exposure time, pull away the cardboard covering the small hole, and close it at the scheduled exposure time.
4． Loading and unloading films: A single piece of 60×60 mm2 film is often not easy to buy, so large films need to be cut. Loading, unloading, and cutting the film must be done in a light-tight darkroom.
Notes
1. Be careful when making, there should be no light leakage.
2. The pinhole should be round and the edges should be smooth.
3. Because the exposure time is long, it is better to shoot still life.
Shoe slippers are a lightweight and non-bending mopping tool.
Preparation method: 1. Shoe slippers are larger than the shoes you usually wear, so they are easy to put on your shoes.
2. Use rag strips as mop strips on the soles of the shoes, and nail a thicker plastic bottom on the mop strips, which is both waterproof and durable.
3. Use cloth shell and waterproof cloth to make the shoe upper, and install a zipper on the back of the shoe upper to make it easy to put on and take off. Connect the upper and sole to make the slippers.