1. We know that we usually find old batteries in our drawers, but we don't know if they still have power. It would be difficult to put electrical devices to check and we cannot know the remaining power. . So you can make a small electroscope.
The method is as simple as this: use a small bulb, a very small one (like that of a pendant light or a toy lamp, available at a hardware store). 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 bulb, you can judge the battery power.
2. Take a broken umbrella, remove the cloth, take a wire, connect one end to TV or radio and the other end to umbrella, it will be a good sig receivernal. If you want to be more professional, simply wrap a few extra turns of wire around the umbrella. It's the cheapest, fastest and just a bit fun way.
3 Assemble a match and a large sewing needle, wrap them tightly with cigarette foil, then fold the end of the foil with the match head to seal it hermetically. Then install a directional fin near the tail, remove the needle and it becomes a very simple recoil rocket.
During the experiment, place the small rocket on the metal stand, light a match and heat it at the part of the aluminum foil tube with the match head. When the temperature reaches the ignition point of the match head, the match box in the foil ignites, causing the surrounding air to expand rapidly, and the gas is ejected from the rear port at high speed . Due to therecoil effect, the rocket launcher flew forward from the mount.
If you wrap two matches placed end to end in aluminum foil, the two ends will not be closed. Place it and heat from the middle. When the match in the cylinder is lit, gas spurts out from both ends, and the aluminum foil cylinder always remains on the stand, thus illustrating the conservation of momentum of the system.
4 Rivet two identical protractors. in the center of the circle and make them flexible. Rotate and make a 1 cm long gap along the right end of the protractor above. When measuring the angle, make its opening coincide with both 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, then draw two rays along the opening to finish. This type of rapporteur can beAlso 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 the small productions of my classmates from the time.
What he made was a small model of an electronic scale. Note that this is a model and can only weigh very light objects, like two small pieces of paper. The materials needed for manufacturing are: a piece of wood (preferably thin, not too big), a washer, a paper clip, an awl, a soldering iron, some 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 a punch to make a small hole in the middle ofthe board, bend a paper clip into a hook shape and attach it to the board through the hole perpendicular to the board. The hook can be hung. Just keep the seal in place. Then take two paper clips and straighten half of them, leaving only one crease. In fact, the straightened part is the arm of the scale, and the remaining bent part is the pan. Do the same with the other paperclip. Then solder the two paperclips and washer together, with the washer in the middle and the paperclips in a straight line. Then hang the washer on the hook and adjust the distance between the hook and the board to approximately 3 mm. Then attach two paper clips under the two trays and prepare LEDs as indicator lights next to the paper clips. With the circuit installed under the board, the scale acts as a single-pole, double-throw switch. This circuit is equivalent to two loops sharing a power supply and two light-emitting diodes. As long as the left side is flowing,the left board will be connected to the pin below, so the circuit is connected and the diode lights up if the weight of both sides is equal, the circuit is blocked and both diodes do not light up; up.
I added more, hope you like it!
Finally, I wish you success and good mood!
Reference materials:
http://zhidao.baidu.com/question/38869004.html?fr=qrl31. Little Balance
Warm reminder: This must be done with the help of parents!
1. First cut the plywood into A, B, C and D.
2. Make an opening 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 top of B, but be careful not to nail it dead and allow it to move freely.
5. Cut a crescent-shaped target board out of plywood and mark it with boards.go.
6. Cut out another small strip and attach it to A with all-purpose glue as shown in the picture.
7. Cut two circular pieces of equal size.
8. Drill four small holes on each side.
9. Cut a small groove on each side of A.
10. Tie the disk with a thin thread and the scale is ready.
Then you can use your imagination to decorate the small scale. After the experience, you can also use it as a small ornament. It really kills two birds with one stone!
：http://www.student.gov.cn/image/6982.jpg
Second, actors walking the tightrope
Actors always get a long stick A. Perhaps people will ask: doesn't this add to the burden on the actors? After completing the following experiment, you will change this view.
1. Material
A piece of white cardboard, a piece of wire 10 cm long, a punaise, a ball of plasticine, a piece of thin iron sheet 30 cm long and 2 cm wide, adhesive tape, glue, scissors, ruler, etc.
2. Production
1. Cut out a small person shape from hard paper and draw five of them. Officially, paint it with color, glue a backing strip to the back, bend the villain's feet forward, fold the backing strip back the back, stick a thumbtack with glue, cut off the excess and bend the tip of the thumbtack towards the back.
2. Straighten the wire, use modeling clay to pinch two small balls of the same size, attach them to both ends of the wire, and then use tape to stick the middle part of the wire. the villain's "hands" can stand upright.
3. Place a ruler vertically against the center paper of the iron sheet, bend the iron sheet at right angles, place it diagonally on the table with the corner down, fix it aWith tape, place the figure upright and align the nail hook with the groove, the villain can slide slowly from the top while remaining smooth.
3. Revealing the secret
Objects are subject to the earth's gravity. The balance of an object depends on the position of its center of gravity. , the more stable the object is. The long and drooping stick can lower the center of gravity. The extra weight also helps with balance, so the actor holds a stick when walking the tightrope.
：http://www.student.gov.cn/image/6261.jpg
Third, the production of hot air balloons (Kongming Lantern)
We gets up and we make a hot air balloon. Hot air from a hair dryer can make it rise slowly, just like a real hot air balloon.
1. First, we use soft paper to cut 6-8 pieces of leaf-shaped paper.
2. Fold them in half and glue their edges together to make a balloon.
3. Use masking tape to stick the four connecting wires to the bottom of the balloon. Use modeling clay to attach the other end of the string to the table.
4. Try to set the speed of the hair dryer as slowly as possible. Point the fan outlet upwards, toward the bottom opening, and turn on the switch. The balloon will slowly grow, tighten the string and rise off the table.
You can make a turtle that can sweep the ground. Do you have a shoe brush? Grind the handle of the shoe brush, press it with the driver motor, then stick a cake plate on it. a little decoration. , start the engine, and the little turtle is gone!
Prepare the materials and tools to make a sand table: frame, chenille, paint, grass powder, turf, silicone gun, old newspapers, white glue, gypsum, etc.
If necessary, you can design it yourselfe the shape and height of the track and use hot silicone to glue it together. (Note: It must be firmly stuck and cannot be loose or tilted)
Add textured paper to the rail to prevent debris from entering during the production process and must not be removed. Use newspaper scraps to shape the pre-made shape, which can be fixed with textured paper, then covered with a plaster bandage and sprayed with clean water.
Once the basic shape is fixed, plaster is poured over it, which will make the whole shape stronger and easier to paint. (Note: Be careful to avoid marks when pouring the plaster)
Glue the building to the already made shape.
When it comes to coloring, be careful to paint dark colors first, then medium colors and finally highlights to create a weathered effect, then plant some vegetation.
After planting vegetation and sappowdered with grass powder, the simple process is basically finished. When you make the sand table, remember to hit the track with sandpaper at the end, and that's it.
Let's make a Kongming lantern!
He can fly by himself!
2.1 Material selection and production
① Take a large, extremely thin plastic handbag and cut the handle flat.
②Take a thin copper wire about 60 cm long (you can use a copper wire made of several strands of soft copper wire) and tie the two ends on both sides of the opening of the practical bag.
③ Wind an appropriate amount of cotton in the middle of the thin copper wire and a simple Kongming lantern is made. As picture shows.
2.2 Unlocking
Choose a windless place (indoor is also acceptable), hold the two corners of the bottom of the practical bag with both hands, so that the openingis turned downwards. , and make the cotton wrapped bag. The thin copper wire hangs naturally. Then pour an appropriate amount of alcohol on the cotton, ignite the alcohol, and after a few tens of seconds, the Kongming Lantern will rise into the sky.
2.3 Remarks
① Alcohol cotton should not be too heavy. Generally, the total mass (total mass of the handy bag, fine copper wire and alcohol cotton) can be less than. 5g and it's easier to remove.
②The length of the fine copper wire should be appropriate so that the plastic bag will not melt after the alcohol burns, and precautions should be taken to avoid 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
The actors are still holding a long piece of wire during tightrope stick shows. Maybe peopleThey will ask: does this not increase the burden on the actors? After completing the following experiment, you will change this view.
1. Material
A piece of white cardboard, a piece of wire 10 cm long, a drawing pin, a ball of plasticine, a piece of thin iron sheet 30 cm long and 2 cm wide, adhesive tape, glue, scissors, ruler, etc.
2. Production
1. Use cardboard to cut out the shape of a small character, draw the facial features, paint it with colors, glue a support strip to the back and bend the little one's feet forward, fold the support strip, stick a thumbtack with glue, cut off the excess and fold the tip of the thumbtack over.
2. Straighten the wire, use modeling clay to pinch two small balls of the same size, attach them to both ends of the wire, and then use tape to stick the middle part of the wire. the "hands" of the wicked canstand.
3. Place a ruler vertically against the center paper of the iron sheet, bend the iron sheet at a right angle, place it diagonally on the table with the corner down, secure it with tape, place the figure upright and align the nail hook with the groove, the villain can slide slowly from the top while remaining smooth.
3. Revealing the secret
Objects are subject to the earth's gravity. The balance of an object depends on the position of its center of gravity. , the more stable the object is. The long and drooping stick can lower the center of gravity. Increasing weight is also beneficial for balance. Therefore, actors must hold a stick when walking the tightrope. Pinhole camera
Method:
Pinhole camera
A pinhole imager can be created based on the principle of pinhole imaging, and clear images can be views on its screen., if you install a photo filmsensitive to the location of the screen, you can still take sharp photos, which becomes a pinhole camera but this requires a "shutter" and a slot to hold the film; In addition, the waterproof requirements are more stringent than ordinary small-hole imagers.
The structure of the pinhole camera is shown in Figure 10.6-l. The body is made entirely of horse manure paper and is divided into two parts: a front cover and a rear cover.
Production method
Draw on the horse manure according to the dimensions of Figure 10.6-2, 10.6-3, 10.6-4 (δ is the thickness of the manure paper horse) On the paper, cut along the solid lines of each image, then use a knife to gently cut along the dotted lines, but do not cut through it, so that a straight edge can form when folding . Then paint both sides of each piece black.
Fold the diapercut out exterior of the front cover (Figure 10.6-2) at 90° along the dotted lines to form a five-sided paper box (the small tab is glued to the outside of the box). Stick the tape. Then stick a piece of black 120 film lining paper on the side with the round hole, and use a needle to pierce a small hole in the lining paper in the center of the hole, with a diameter of about 0.4mm ( a No. 12 sewing needle has a diameter of approximately 0.4 mm). As shown in Figure 10.6-1, a paper slot is placed 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 .
Fold the cut inner layer of the front cover (Figure 10.6-3) 90° along the dotted lines to form a square tube, and glue the interface (the uvula is glued inside square tube). . Then fold the langTrapezoidal uets at the end with the gap in a paper frame, align the reinforcement frame (Figure 10.6-4) with the gap and glue them together. Cut a paper frame from cardboard according to the size of the reinforcement frame, align the notches and attach it to the reinforcement frame, and use strips of tape to stick the paper frame to the square tube at the outside. A paper frame is formed between. the reinforcement frame and the cardboard slot, the film can be loaded or removed from the side thanks to the notch is designed to facilitate loading and unloading of the film. After the inner layer is completed, it should be glued with the outer layer, that is, bend each trapezoidal tab on the other end of the square tube 90° along the dotted line, apply glue, align the gaps and insert the outer layer. layer while inserting the inner and outer layers on each side. Insert a piece ofhorse manure paper in between to make sure the space between the inner and outer layers on each side is the same after the front end of the inner layer is firmly stuck. On the side with the round hole on the outer layer, remove the inserted piece of horse manure paper and the front cover is ready.
As for the production of the back cover, except the side width is 80＋26mm and there are no holes on the bottom, everything else is the same as producing 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.
How to use
1. The pinhole camera has a fixed image distance of approximately 64mm and a light transmission aperture of 0.4mm, so the aperture is also fixed. Experiments show that the opening number is about 160. When the brightness of the photographed scene 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 aperture time. exposure equal to the square of the aperture ratio (i.e. t1:t2). =(F1:F2)2). For example, take For a certain scene, if the exposure time is 1/30 second with an aperture of 16, then the exposure time should be 3.3 seconds with a pinhole camera with an aperture of 160. The time Optimal exposure must also be determined experimentally.
2． The method of framing when taking photos with a pinhole camera is shown in Figure 10.6-5. Place one eye near the middle of one side and “aim” toward both ends of the opposite side. Then the part taken in this angle is the scope of theingestion. Moving the distance between the camera and the subject can change the size of the image.
3． Exposure: Choose the scene to photograph, calculate the exposure time, remove the cardboard covering the small hole and close it when the programmed exposure time is reached.
4． Loading and unloading film: A single piece of 60×60 mm2 film is often not easy to purchase, so it must be cut from a large film. Loading, unloading and cutting of films must be carried out in a light-tight darkroom.
Remarks
1. Be careful during manufacturing and there should be no light leaks.
2． The pinhole should be round and the edges should be smooth.