Please tell me a little physics experiment, what kind of physics experiment is this?

Perforated pieces of paper hold water.

As you know, anything with holes will leak. However, now you will see a thin piece of paper full of small holes, which can actually hold up a pound or even two pounds of water, without leakage.

1 Equipment A large empty bottle, a piece of paper with a large needle piercing many small holes, and a large glass of colored water.

2 Performance process.

Fill a large empty bottle with colored water; Cover the mouth of the perforated piece of paper and press the piece of paper with your hand, turn the bottle upside down so that the mouth of the bottle is facing down, and gently remove your hand. The paper lid the bottle without moving, and the water did not come out of the hole.

When performing, it should be noted that the bottle should be a small-mouthed bottle (such as a large-mouth bottle, and the paper should be harder), and the fuller the bottle of water, the better the effect. After inverting the bottle mouth, the hand should be slowly and gently removed to avoid leakage of the paper without the lid being flat, or even the water from pouring out.

3 Explanation The thin piece of paper can hold the water in the bottle because the atmospheric pressure acts on the paper, creating an upward supporting force. The hole does not leak water because the water has surface tension, and the water forms a film of water on the surface of the paper, so that the water does not leak out. It's like an umbrella made of cloth, which doesn't leak rain even though it has many small holes.

A table tennis ball.

A bottle with a caliber slightly smaller than the radius of a ping-pong ball (can not make a plastic bottle) some waste paper. Light the waste paper, throw it into the bottle, and quickly place the ping pong ball on the mouth of the bottle.

Soon, the ping-pong ball was tightly tied to the mouth of the bottle.

Indicates that atmospheric pressure is present.

If you can't hold a ping pong ball, consider heating the bottle.

Light travels in a straight line.

Equipment: A beaker (with mixed water) A red laser light Steps: 1. Place the beaker on the table.

2. Use a laser light to shine into the cup, and you can see that the light is propagating in a straight line.

Put the thermometer indoors for a period of time, after the temperature is stable, fan the thermometer to see that the temperature has not dropped (it will not drop), dip the thermometer in some alcohol, and then fan, and see the temperature drop, indicating that the liquid evaporates and absorbs heat.

In the same way, it will be cool when the wind blows after swimming or bathing)

Take a small ball and release it freely.

Experiment with gravity downwards!

It is a photoelectric effect experiment, but the current should be measured, the principle is that the light on the metal will cause the electrons in the metal to overflow, and the forward voltage between the two metal plates will make the current reach the metal plate on the other side, so that there is a current flowing through the circuit, and the current is measured by the ammeter.

This is a famous experiment on the photoelectric effect, and Einstein won the Nobel Prize for successfully explaining the photoelectric effect and proposing the quantum of light.

In fact, in the photoelectric effect experiment, as long as the optical frequency is large enough and the distance between the metal plates is small enough, the current can be measured without adding voltage or even adding reverse voltage.

It should be an experiment of the photoelectric effect, after a certain frequency of light irradiates the metal, due to the sufficient energy, the photon will be absorbed by the electron and break away from the metal, fly out, and be absorbed by the opposite metal, turning the original open circuit into a path, and the intensity of the passing current and the containment voltage can be measured.

……That shouldn't be a disconnected wire, guess it's a photoresistor ......

Since it is related to light, is it a photoresistor? When there is no light, the resistance is very large, which is equivalent to an open circuit, and when there is light, the resistance is very small, which is equivalent to a path, I wonder if the explanation is correct?