How to calculate electric field force
then it is clear at a glance,
1) positive charge and negative work, indicating ua-ub & lt; 0
2) negative charge and negative work indicate ua-ub & gt; 0
3) the potential energy of point a is less than B, which is equivalent to the positive work of electric field force from a to B, then the negative charge and positive work indicate that ua-ub & lt; The relationship between the direction of electric field force and positive work and negative work
the positive work of electric field force is equivalent to the decrease of electric potential energy
the positive charge has higher electric potential energy at the high potential point
the negative charge has higher electric potential energy at the low potential point
electric field force between two charges: F = kq1q2 / R ^ 2, K is electrostatic constant
The direction of the electric field force on the positive charge at a certain point is the same as the direction of the electric field strength at that point (or along the tangent direction of the electric field line). The direction of the electric field force on the negative charge at a certain point is opposite to the direction of the electric field strength at that point
The larger the current is, the greater the electric field force is, and the higher the current is, the denser the electric field lines are. Therefore, the judgment of electric field force depends on the density of electric field lines. For example, the electric field force of an electromagnet is not determined by the electromotive force, but by the current (generated by adjusting the impedance generated by the inctance) to determine the magnetic strength generated by the electric field force. That is, the higher the current is, the denser the electric field lines are, and the denser the electric field lines are, that is, the stronger the magnetism is The interaction betweencharges occurs through the electric field. As long as there is a charge, there is an electric field around the charge. The basic property of the electric field is that it has a powerful effect on the charge placed in it
extended data:
the interaction between charges occurs through the electric field. As long as there is a charge, there is an electric field around the charge. The basic property of an electric field is its powerful effect on the charge placed in it. This force is called electric field force
the electric field force is the force on the charge when it is placed in the electric field. Or the force exerted in an electric field to move a free charge. Its magnitude can be obtained by Coulomb's law. When there are multiple charges acting at the same time, its size and direction follow the rules of vector operation
electric field has the properties of force and energy. The physical quantities describing electric field include electric potential, electric potential energy, electrostatic force, electrostatic force work, etc. in order to better describe electric field, there are also electric field line, equipotential surface and other concepts, which can judge the electric potential from multiple angles&# 8194;
The potential along the direction of the electric field line is lower and lower&# 8194; In the electric field generated by positive charge, the closer to the charge, the higher the potential; in the electric field generated by negative charge, the closer to the charge, the lower the potential If the potential at infinity is zero, the potential around the positive point charge is positive and that around the negative point charge is negative&# 8194; According to the movement of charge only under the action of electrostatic force. Only under the action of electrostatic force, the charge starts to move from static, and the positive charge always moves from the point with high potential to the point with low potential; The negative charge always moves from the point with low potential to the point with high potential. But they all move from the point with high electric potential energy to the point with low electric potential energyelectric field force
1. Definition: the interaction between charges occurs through the electric field. As long as there is a charge, there is an electric field around the charge. The basic property of the electric field is that it has a powerful effect on the charge placed in it. This kind of force is called electric field force< Direction: the positive charge is along the tangent direction of the electric field line, and the negative charge is along the opposite direction of the tangent direction of the electric field line< Calculation: the formula of electric field force is f = QE, where q is the charge of point charge and E is the field strength. Or w = FD, it can also be calculated according to the distance between the work done by the electric field force and the movement in the direction of the electric field force. Another important formula w = Qu (where u is the potential difference between two points) in electromagnetism is derived from this formula
the electric field force is the force exerted on the charge when it is placed in the electric field. Or the force exerted in an electric field to move a free charge. Its size can be obtained by the vector operation rule of Coulomb's law. When there are multiple charges acting at the same time, its size and direction follow the rules of vector operation
function
e to the wide role of electric field force, it is applied to ion accelerators, navigation correction in aerospace instry, processing of new materials, change of material arrangement and so on<
research direction.
in the future, with the existence of electric field force, aerospace instry will make great progress, such as the use of electric field protection layer (which can make aircraft lighter); And let the aircraft rely on the electric field to fly (instead of the existing engine); Electric fields play a role in the decay of nuclear matter.
next, determine the direction of the force on the charge
if there is an electric field line that can be used, of course, it is good. The direction of the electric field line is the force direction of the positive charge, and the direction opposite to the direction of the electric field line is the force direction of the negative charge
if there is no electric field line, it depends on the electrical properties of the electric charges that generate the electric field, and uses the principle of same-sex repulsion and opposite-sex attraction to judge the direction of force
finally, look at the speed of its movement, and then compare with the direction of the force judged before, the angle between them is less than 90 degrees, that is, the electric field force does positive work on the charge, and the electric field force greater than 90 degrees does negative work
if the angle is 90 degrees, the electric field force does not work,
because the initial velocity of the positive charge is zero, it goes along the direction of the force, the direction of the force of the positive charge is the direction of the electric field line, and along the direction of the electric field line, the potential is reced
2,
definition: the direction of the field strength (i.e. the direction of the electric field) of a point in the electric field is the same as the direction of the electric field force on the positive charge
judgment:
(1) the direction of positive charge force is the direction of power plant
(2) the opposite direction of negative charge force is the direction of power plant
(3) the electric potential energy decreases along the direction of electric field
1. In a uniform electric field, a point of charge is moved from point a to point B, and the distance between two points a and B along the direction of field strength is set as D. now, q is moved from a to B along three different paths. It can be proved that the work done by the electric field force WAB = QED, that is, the work done by the electric field force has nothing to do with the path of the moving charge
(1) the formula w = f · s · cos θ This formula is only suitable for uniform electric field and can be deformed to w = QE · s · (2) calculated by w = Qu, this formula is applicable to any form of electrostatic field. When w = Qu is used to calculate the work of electric field force, the sign of Q and u can be substituted together to calculate the positive and negative of W, or only the absolute value of Q and U. then the positive and negative of work can be judged according to the nature of charge, the direction of electric field force and the moving direction
extended data
electric field has the nature of force and energy. The physical quantities describing electric field include electric potential, electric potential energy, electrostatic force, electrostatic force work, etc. in order to better describe electric field, electric field line, equipotential surface and other concepts can be used to judge the electric potential from multiple angles&# 8194;
The potential along the direction of the electric field line is lower and lower&# 8194; In the electric field generated by positive charge, the closer to the charge, the higher the potential; in the electric field generated by negative charge, the closer to the charge, the lower the potential If the potential at infinity is zero, the potential around the positive point charge is positive and that around the negative point charge is negative&# 8194; According to the movement of charge only under the action of electrostatic force. Only under the action of electrostatic force, the charge starts to move from static, and the positive charge always moves from the point with high potential to the point with low potential; The negative charge always moves from the point with low potential to the point with high potential. But they all move from the point with high electric potential energy to the point with low electric potential energyelectric field strength: e = f / Q (definition formula, calculation formula, electric field strength is its own property, independent of electric field force and electric quantity)