Where is the insulating paint scraped away from the resistance wire on the rheostat? Why?

Where is the insulating paint scraped away from the resistance wire on the rheostat? Why?

The insulating paint has been scraped away from the place where the slide contacts
The outer layer of the resistance wire must have insulating paint to prevent the winding resistance wires from short circuit. The sliding rheostat is connected to one end of the resistance wire and the slide, so the resistance wire must be connected with the slide

Function of sliding rheostat

The function of sliding rheostat is to protect the circuit. In different experiments, it has other functions. For example, "study the relationship between resistance and current and voltage" regulates the voltage at both ends of the fixed value resistance. Many experiments show that the general rule is that "study the relationship between current and resistance" controls the voltage at both ends of the resistance to be the same

What is the function of each structure of sliding rheostat?

The two terminals above the connection point for the circuit are equivalent to one terminal. For the convenience of connection, the two terminals below are respectively connected with both ends of the resistance line. The principle of connection is "one up and one down" slide. Change the length of the resistance line in the access circuit to achieve the purpose of changing the resistance of the access circuit

Structure diagram of sliding rheostat

① : resistance wire; ②: terminal; ③: slide; ④: metal rod; ⑤ support