Small inventions and small creations of elementary school students

1. We know that we usually find some old batteries in the drawer, but we do not know if there is still no electricity, if you put into the electrical appliances to test is very troublesome and can not know the amount of electricity remaining. So you can make a small checker.

The method is simple as follows: use a small bulb, very small kind (like a pendant or toy light on the hardware store are sold). Then use two thin enameled wire connected to the lamp 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 charge.

2. Take a broken umbrella, remove the cloth, take a wire, connect one end to a TV or radio, and one end to the top of the umbrella, which is a good signal receiver. If you want to be more professional, just wrap a few more turns of wire around the top of the umbrella. It's the cheapest, quickest way to do it, just kinda funny.

3 Put a match and a large needle from a quilt together, wrap them tightly in aluminum foil from a cigarette pack, then bend the foil over the end with the match head to seal the twist. Then put a directional tail near the end, pull the needles out, and you have a very simple recoil rocket.

To experiment, place the small rocket on a wire stand, light a match, and heat it against the part of the aluminum foil tube wrapped with the match head. When the temperature rises to the ignition point of the match head, the matchbox in the foil is ignited, causing the surrounding air to expand dramatically, and the gas is ejected from the tail port at high speed. Due to the recoil effect, the bazooka then flies forward from the rack.

If you wrap two matches placed head to head in aluminum foil, neither end is closed. Place it on and heat it from the center. When the matches in the tube ignite, gas is ejected from both ends and the aluminum foil tube remains on the rack, thus illustrating the conservation of momentum of the system.