Point charge refers to the charged body whose linearity is much smaller than the distance between them in physics. Kinematic equivalent of particle "model.
All charges have volume and size. There is interaction between charges, the same kind of charges push each other, and the different kinds of charges attract each other. When quantitatively studying the interaction between charges, it is found that the size of some charges has little impact on the results of the studied problem. At this time, the volume and size of charges can be completely ignored, and charges can be regarded as charges with only electric quantity but no size. This is the point charge model.
Definition of point charge:
Point charge is an ideal model of charged body. If the shape, size and charge distribution of the charged body can be ignored in the research problem, it can be regarded as a geometric point, then such charged body is a point charge. Whether a real charged body can be regarded as a point charge is not only related to the charged body itself, but also depends on the nature of the problem and the requirements of precision. Like the concepts of particle and rigid body, point charge is the abstraction and approximation of the actual charged body. It is an indispensable ideal model for establishing the basic laws with universal significance, and an indispensable analytical method for transforming or decomposing complex and diverse practical problems into basic problems. For example, the establishment of Coulomb's law and Lorentz's force formula, the quantitative study of the electric field generated by charged bodies and the interaction between charged bodies, the introduction of test charges, etc., are inseparable from point charges.
The actual charged body (including electrons, protons, etc.) has a certain size and is not a point charge. When the distance between charges is large enough to consider that the size and shape of charges do not play a role, the charge can be regarded as a point charge.
Understanding of point charge:
Point charge "is a charged body, which is a geometric point without size and shape. And the charge is all concentrated on this geometric point. In fact, any charged body has its size and shape. The real point charge does not exist. Like the concept of "particle" in mechanics, it belongs to an idealized model. However, when we study the interaction between charged bodies, if the geometric linearity of charged bodies is much smaller than the distance between them, then the influence of the shape, size and charge distribution of charged bodies on the interaction between charged bodies can be ignored. In this case, we can still abstract the charged body into a point charge model. Only in this way can the concept of "distance between charges" itself have a completely definite meaning. From this point of view, point charge is also a concept of relativity. In order to better understand the relativity of point charges.
What is point charge physics knowledge
Point charge is only an ideal state of physics to ignore the shape of charged body
Size, etc., so as to facilitate the research and calculation. Of course, the shape of the point-to-point body is required to become a point charge
The size has little influence in the research and calculation, and the error is allowed. You misunderstood the two just to let you understand the size of the impact, but not the absolute condition
Does point charge refer to charged objects or microscopic charges?
Point charge, an ideal model.
It can represent charged objects as well as microscopic charged particles.
Conditions that can be regarded as point charge:
The size of the charged body (or particle) itself is negligible or much smaller than the distance between the charged bodies (or particles) studied.
