Why is there an electric spark when I take off my sweater?

Due to the dry air, the body comes into contact with the sweater, and there will be static induction, and the spark is static electricity.

Because the air is dry, the sweater rubs a lot of air, generating static electricity.

This is the physics of electricity that I learned in junior high school before, a kind of glass rod that has been rubbed by silk, they will repel each other, called "glass electricity"; The other is the rosin that has been rubbed by the fur, and it will attract each other to the glass rod rubbed by the silk, which is called "rosin electricity".

In the case of dry winter, the friction between the body and the sweater can generate static electricity, also known as electric sparks.

It is a natural phenomenon of static electricity, the air is dry, and friction produces static electricity.

EDM is a machining process that uses a discharge electrode (EDM electrode) with a specific geometry to cauterize the electrode geometry on a metal (conductive) part. The EDM process is commonly used in the production of stamping and casting dies.

This belongs to fluids, and Franklin also proposed the "single-stream theory", that is, electricity is actually a fluid that exists in all objects.

The sweater was very nice and very warm.

A kind of glass rod that has been rubbed by silk, they will repel each other, which is called "glass electricity"; The other is the rosin that has been rubbed by the fur, and it will attract each other to the glass rod rubbed by the silk, which is called "rosin electricity".

Removing sweaters in winter will cause electric sparks because of static electricity. Static electricity is a kind of electric charge that is at rest or does not flow (the flowing charge forms an electric current). Static electricity is formed when the charge is gathered on an object or surface, and the charge is divided into two types: positive charge and negative charge, that is to say, the phenomenon of static electricity is also divided into two types, namely positive static electricity and negative static electricity.

When the positive charge is gathered on an object, it forms positive static electricity, and when the negative charge is gathered on an object, negative static electricity is formed, but whether it is positive static electricity or negative static electricity, when the electrostatic object touches a zero-potential object (grounded object) or an object with a potential difference, the charge transfer will occur, which is the spark discharge phenomenon we see every day.