How to calculate electric potential energy and what is the electric potential energy formula

1.Electric field force to do work:

Because w ab=quab=q( a- b)=q a-q b=ea(beginning) — eb(end)= - e, (ea(beginning), eb(end) are the potential energy of the two points). The relationship between the work done by the electric field force and the change of electric potential energy: wab>0, eq<0, the electric field force does positive work, and the electric potential energy decreases and is converted into other forms of energy; WAB<0, EQ>0, the electric field force does negative work, and the electric potential energy increases and other forms of energy are converted into electric potential energy.

Along the electric field line, a b moves, if it is positive, then wab>0, then uab = a- b>0, then , then positive eq; If negatively charged, then wab<0, then uab = a- b>0, then , then negative eq. Against the electric field line, b a moves, if it is positive, then wab<0, then uab = a- b<0, then , then positive eq; If negatively charged, then WAB>0, then UAB= a- b<0, then , then the work done by the negative EQ electrostatic force is equal to the reduction of electric potential energy WAB=EPA-EPB

2.Potential Difference:

eq=wao=q·φa.(eq denotes electric potential energy, a denotes potential difference): when a>0, q>0, then eq>0, q<0, eq<0; When a<0, q>0, then eq<0, q<0, then eq>0

3.Kinetic energy theorem:

1) The electric field force does positive work, the electric potential energy decreases, and the kinetic energy increases. That is: electrical energy is converted into other forms of energy (kinetic energy) (2) The electric field force does negative work, the electric potential energy increases, and the kinetic energy decreases. That is, other forms of energy (kinetic energy) are converted into electrical energy.

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Isn't there a formula in the book?

Electric potential energy: ea q a, ea: electric potential energy of a charged body at point a (j), q: electric charge (c), a: electric potential at point a (v).

e=kq1q2 r 2, Coulomb force.

Assuming that the charge q is fixed now, then when q moves from where the distance from q is r1 to where r2 (r1 is definite integral.

w=∫dw=∫fdr=∫(kqq/r^2)dr=kqq∫（dr/r^2）= kqq∫d（1/r）。The integration interval is r1 to r2, so there is w=-k r2 - 1 r1) =kqq r1 - kqq r2.

Potential energy in an electrostatic field. The difference between the potential energy of a charge at two points in the electrostatic field (e.g., points A and B) is equal to the electrostatic force when it moves from point A to point B.

The work done. Therefore wab=qed (e is the electric field strength at that point.

d is along the line of the electric escort field.

, the electric potential energy is common to the charge and the electric field, and has a unity.

Electric potential energy reflects the energy that the electric field and the charge in it have together.

The electric potential energy can be determined by the electric field force.

Work is done to obtain because wab=quab=q( a- b)=q a-q b=ea(beginning)-eb(end)= e, is the electric potential, and q is the amount of charge.

u is the potential difference.

EA (beginning) and EB (end) are the potential energy of the two points).

Electric potential energy: ea q a, ea: electric potential energy of a charged body at point a (j), q: electric charge (c), a: electric potential at point a (v).

e=kq1q2/r^2。

Then under the action of the Coulomb force, the microwork done when the charge moves a tiny distance dr dw=fdr.

Relationship: According to the law of conservation of energy, it can also be obtained that, in general, the relationship between the change of kinetic energy and the change of electric potential energy of the moving charge without external force doing work.

If it is an external force that increases the electric potential energy, then the other forms of energy are converted into electric potential energy, the external force does positive work, the electric field force does negative work, and the electric potential energy increases.

If it is the electric field force that makes the object move, then the electric potential energy is converted into kinetic energy, and the electric field force does positive work, the kinetic energy of the object increases, and the electric potential energy decreases.

If it is the motion of the object that increases the electric potential energy, then the kinetic energy is converted into electric potential energy, the kinetic energy of the object decreases, the electric field force does negative work, and the electric potential energy increases.

Since the work done by the electrostatic force when the charge is moved is not related to the path of the movement, the charge also has potential energy in the electric field, this potential energy is called electric potential energy, the change of electric potential energy is only related to the work of the electric field, and the work done by the electrostatic force is the decrease of electric potential energy.

The electric potential energy can be based onElectric field forceThe amount of work done and the amount of electric potential energy changed by the electric potential energy of the object become larger, which is the process of negative work done by the electric field force, and the amount of work done and the amount of electric potential energy changed are inAbsoluteis equal on . On the contrary, if the electric field force does positive work, the electric potential energy decreases correspondingly.

Electric potential energy: ea q a {ea: electric potential energy of a charged body at point a (j), q: electric charge (c), electric potential at point a (v)}

e=kq1q2/r^2

Potential energy in the electric field of the reflux of the resting limb. The difference between the potential energy of a charge at two points in the electrostatic field (e.g., point A and point B) is equal to the electrostatic force when it moves from point A to point B.

The work done. Therefore wab=qed (e is the electric field strength at that point.

d is along the electric field line.

, the electric potential energy is common to the charge and the electric field, and has a unity.

The electric potential energy can be obtained from the work done by the electric field force because wab=quab=q( a- b)=q a-q b=ea(beginning)-eb(end)= e

Judgment of charge size

1.Field source charge judgment method: positive charge of the field source.

The closer it gets, the greater the potential energy of the positive charge and the smaller the potential energy of the negative charge.

2.Electric field line method: When the positive charge moves along the direction of the electric field line, the electric potential energy gradually decreases, and when it moves against the direction of the electric field line, the electric potential energy gradually increases.

When the negative charge moves in the direction of the electric field line, the electric potential energy gradually increases, and when it moves against the direction of the electric field line, the electric potential energy gradually decreases.

3.Work judgment method: Regardless of positive or negative charge, the electric field force does positive work, the potential energy of the charge must decrease, and the electric field force does negative work, the potential energy of the charge must increase.

The zero potential energy can be arbitrarily selected, but in theoretical research, the electric potential energy at infinity or the earth is often taken as 0

Take infinity as potential zero: >0 in the electric field generated by the positive charge, far away from the field source charge: move the positive test charge w>0, ep;

Move the negative test charge w<0,ep.

The electric field generated by the negative charge is <0, far away from the field source charge: moving the positive test charge is starving w<0, ep;

Move the negative test charge w<0,ep.

The formula for electric potential energy is ep=wao=q· a=qua. EP denotes the electric potential energy and A denotes the electric potential at point A. The electric potential energy formula is related to the electric field, the charge in the electric field, and the selection of the zero point of the electric potential energy, for the point charge.

The potential energy of the electrostatic field generated by the electric quantity q is related to the distance r from the spatial position of the first group q to the position of the point charge: we kqq r. where k is a constant.

Potential energy significanceElectric potential energy is the potential energy of the charge distribution in the electric field, and the configuration of the charge distribution inside the system.

Relate. The unit of electric potential energy is joules.

Electric potential energy is not the same as electric potential. Electric potential is defined as the electric potential energy possessed by a charge in an electric field per unit charge. The unit of electric potential is volts.

The electric potential energy reflects that the electric field and the electric charge in it together have the energy of the orange.

The total potential energy is simply to multiply each charge by its potential.

In electrostatics, electric potential energy is the potential energy of the charge distribution in an electric field, which is related to the configuration of the charge distribution within the system. The unit of electric potential energy is joules. Electric potential energy is not the same as electric potential.

Electric potential is defined as the electric potential energy possessed by a charge in an electric field per unit charge. The unit of electric potential is volts.

Single-point charge system

A physical system with only a single point charge has zero potential energy, and since there is no other source charge that can generate an electric field, the external mechanism does not need to do any mechanical work on it to move the point charge from infinity to its final position.

In particular, it is possible that this charge may interact with the electric field it generates. However, since the electric field generated by itself at the position of the point charge is infinite, when calculating the finite total potential energy of the system, it is generally not necessary to take this "self-defeat megalophoric body energy" into account to simplify the physical model and facilitate the calculation.

e=q 4 r 2 ,r>r, with the center of the sphere, make a sphere with a radius less than r as a Gaussian surface, because the net charge in the Gaussian surface is zero, so the field strength in the sphere is zero everywhere.

At a certain point in the electric field, the ratio of the electric field force (positive charge) at the test point to the charge carried by it is a quantity that has nothing to do with the charge at the test point. Therefore, the direction of the electric field force experienced by the electric field force at the test point charge (positive charge) at that point is the direction of the electric field.

The direction of the electric field strength at a certain point in the electric field can be determined by the electric field direction of the electric field force at the test point charge (positive charge) at that point. The strength of the electric field can be determined by the ratio of the force on the test charge to the charge charge at the test point.