How to understand electric potential, electric field, how to understand electric potential correctly

Let's start with the electric potential.

Let's put it this way: electric potential is a type of "driving potential", and the reason why the universe moves is due to the "potential difference". The most intuitive example is the flow of water, where the "driving potential" is the height and the "potential difference" is the height difference, without which the water would not flow (e.g. water in a bucket).

The "potential difference" corresponding to the electric potential is the so-called voltage, which is what you say in your textbook that "voltage drives the flow of electrons in a metal conductor", but in fact, the "potential difference" drives the flow of electrons. There are other forms of "potential" in the universe, such as temperature, pressure, etc., and you will understand it when you are rich in knowledge in the future!

About electric fields: The key to understanding electric fields is to understand what a "field" is, and a "field" is another form of "form of existence of matter". The electric field is one of many "fields".

There are two forms of existence of matter, one is in the form of particles and the other is in the form of fields. The more traditional explanation is that the field is intangible, while the particle is tangible.

That is, we can see and touch the particles, but we can't see or touch the field. This explanation is sufficient for high school students.

I would like to share some of my personal insights below, and I hope you will have a deep understanding of the field. I think that fields and particles are two forms of material existence, and their existence can be perceived (particles can be seen and touched, gravitational fields, electric fields, etc., although they are invisible, but we can perceive, for example, when you lift a heavy object, you will feel heavy, "feel heavy", this is another form of perception. ）

These are all handwritten, and I hope you have a deeper understanding of physics!

The electric potential is the result of the accumulation of the electric field along space, that is, the electric potential is equal to the integral of the electric field in a certain direction of space, if it is a uniform electric field, then along the direction of the electric field line, u=ed;

The electric field is the differential of the electric potential versus space, e=du dx, and if the electric potential varies uniformly in a certain direction, then in that direction, e=u d

The stronger the electric field at a certain point, the more obvious the change of the electric potential with space.

The correct understanding of electric potential is:

In the electric field, the ratio of the potential energy of a charge at a certain point to the amount of charge it carries (related to positive and negative, and the potential energy and the positive and negative of the charge can be judged by bringing in both the electric potential energy and the positive and negative of the charge in the calculation), which is called the electric potential of this point, which is usually expressed by .

Electric potential is a physical quantity that describes an electric field in terms of energy, and electric field strength describes the electric field in terms of force. The potential difference can generate an electric current in a closed circuit (when the potential difference is considerable, an insulator such as air can also become a conductor). The electric potential is also known as the potential.

The physical principle of electric potential:

The electric potential is only magnitude and has no direction and is a scalar quantity. Like topography, electric potential is also relative, and in specific applications, the potential energy of the standard position is often taken as zero, so the potential of the standard position is also zero. The electric potential is simply the result of a comparison with a standard position.

We often use the earth as our standard position.

In theoretical research, we often take infinity as the standard position, and in the habit, we often use the term "outside the electric field" instead of "zero electric potential position". The electric potential is a relative quantity, and its reference point can be arbitrarily chosen. Regardless of whether the selected object is charged or not, it can be selected as the zero reference point of the standard position.

For example, the earth itself is negatively charged, and its electric potential is about at infinity. Nonetheless, it is possible to use the Earth as a reference point for zero electric potential, and since the Earth itself is a large conductor, the capacitance is very large.

Therefore, adding or decreasing some charge on such a large conductor has little effect on its potential change. Its electric potential is relatively stable, so in general, the earth is still selected as the zero potential reference point.

The above content refers to Encyclopedia - Electric Potential.

The electric field and the electric potential are interrelated, the electric potential is the line integral of the electric field, the electric field is the gradient of change of the electric potential, that is, the derivative of the electric potential, the faster the electric potential changes, the stronger the electric field, there is a special place, the zero point of the electric potential can be arbitrarily selected, the electric potential can be zero where the electric field is not zero, and the electric field can not be zero where the electric potential is zeroThe relationship between the electric field line and the equipotential surface: the denser the electric field line, the denser the equipotential surface, and the electric field line is perpendicular to the equipotential surface passing through it.

on the Internet.

Field strength and electric potential have no causal relationship. The direction of the field is the fastest direction of electric potential falling, and the small field strength indicates the speed of the electric potential falling along the direction of the electric field line, and there is no causal relationship between the field strength value and the electric potential value.

on the Internet.

3 Relationship between the electric field line and the equipotential surface: The denser the electric field line, the denser the equipotential surface, and the electric field line is perpendicular to the equipotential surface passing through it.

4 field strength. Relationship with electric potential: There is no causal relationship between field strength and electric potential. The direction of the field strength is the direction of the fastest electric potential falling, and the small field strength indicates the speed of the electric potential falling along the direction of the electric field line, and there is no causal relationship between the field strength value and the electric potential value.

3 Relationship between the electric field line and the equipotential surface: The denser the electric field line, the denser the equipotential surface, and the electric field line is perpendicular to the equipotential surface passing through it.

4 Relationship between Field Strength and Electric Potential: There is no causal relationship between field strength and electric potential. The direction of the field strength is the direction of the fastest electric potential falling, and the small field strength indicates the speed of the electric potential falling along the direction of the electric field line, and there is no causal relationship between the field strength value and the electric potential value.

Answer: 3. If the electric field line is not perpendicular to the equipotential surface, then there is a component along the equipotential surface, so that the electric field force of the charge when moving along the equipotential surface.

You can do the work. Therefore, the assumption is incorrect. Therefore, the electric field lines should be perpendicular to the equipotential surface.

The denser the electric field line, the greater the electric field force on the charge, and the more work done by the electric field force when moving the same distance may also be more work done to overcome the electric field force, so moving the same distance along the direction of the electric field line here is worse than the electric potential at the sparse place.

Big. Then, when the difference between adjacent equipotential surfaces is the same, the denser the electric field line, the denser the equipotential surface.

It seems that many people are not clear about this relationship, the electric field and the electric potential are interrelated, the electric potential is the line integral of the electric field, the electric field is the gradient of change of the electric potential, that is, the derivative of the electric potential, the faster the electric potential changes, the stronger the electric field, there is a special place, the electric potential zero point can be arbitrarily selected, the electric potential can be zero where the electric field is not zero, and the electric field can not be zero where the electric potential is zero.

The field strength around the source charge q e(r) kq r , the [electric potential field] u(r) kq r around q (+q forms a positive electric potential field), the author feels that the concept of (electric potential field) is more appropriate than the concept of (electric potential), which reflects that the electric potential field is distributed in a certain spatial range. Put the point charge (-q) into the electric potential field, the point charge has a potential energy w -kqq r (-q has a negative potential energy in q). Quantum mechanics solves the Schrödinger equation for hydrogen atoms, the extranuclear electron (-e) is in the electric potential field of the proton (charge e) (better than the force field), and the extranuclear electron (-e) has the electric potential energy u(r) k·e r, which is the potential energy part of the energy operator h.

Their relationship is manifested by the work done by the electric field force.

When the electric field force does positive work, the electric potential energy decreases, and how much positive work the electric field force does, the electric potential energy decreases.

When the electric field force does negative work, the electric potential energy increases, and the electric potential energy increases as much as the electric field force does negative work.

The power bureau has no spring power.

When doing positive work, the electric potential energy decreases, and vice versa, the electric potential energy increases.

The electric potential decreases in the direction of the electric field line.

Positive charge. The electric potential energy decreases along the direction of the electric field line.

The potential energy of the negative charge increases along the direction of the electric field line.

Moving a positive charge, the potential energy and the electric potential change synchronously.

Moving a negative charge, the potential energy and the potential change in reversal.

The electric field is a special substance.

The physical properties of an electric field can be described in terms of electric field strength and electric potential.

Electric field strength, which indicates the nature of the force of the electric field.

Electric potential, which represents the nature of the energy of an electric field.

It can be seen that electric potential is a physical quantity that represents the energetic properties of an electric field.

1. There is a little problem. In one-dimensional space, the field strength is the negative derivative of the electric potential. Must be negative.

In three-dimensional space, the field strength is the negative gradient of the electric potential. This is dictated by field theory. It can even be said that the field force and field strength are strictly defined by this formula.

I don't know if I can prove it with a simple theory.

This is the truth, even in high school, it should be possible!

2. It is the direction of the electric field. The reason is what 1 says. The gradient determines the direction in which the potential function declines fastest in space, and since the field strength is defined by the negative gradient of the electric potential, the field strength must fall the fastest in the direction of the field strength.

Electric field lines are just contour lines in the electric field, similar to contour lines in geography, and the normal direction of the electric field lines marks the direction in which the electric potential decreases the fastest, that is, the negative gradient direction. And where the electric field lines are dense, it indicates a rapid decline in the electric potential, that is, the gradient is very large, that is, the field strength is very large.

The essence of electric field energy and electric potential energy is the same, both are electrical energy, and the specific differences are as follows:

The electric potential energy is for the work done by the electric field force, as long as the electric field force does the positive work, the electric potential energy decreases; If negative work is done, the potential energy increases; The electric field energy is for the capacitor, for example: when the capacitor is charged, the electrical energy of the power supply is converted into electric field energy; When discharging, the electric field of the capacitor is converted into electrical energy.

In the electrostatic field, we call the electric energy "electric potential energy", which means that the electric field can do work on the charge, so it has energy, and this energy is called electric field energy, but the electric field energy must be reflected by the electric field force when the charge placed in it is moved by the electric field force, and then the electric field energy is called the electric field energy in the electric field.

When an electric field is established in a conductor and free electrons move in a directional manner to form an electric current, the electric field energy is expressed in the form of current energy, which is commonly referred to as "electrical energy".

Zero-based learning of electronics, starting from the initial starting point "atom", from easy to difficult, step by step, take you into the wonderful world of electricity!