The direction of the electric field line is the direction of movement of the positive charge

The electric field line is a visual tool to describe the nature of the electric field force, it can qualitatively describe the direction and strength of the electric field, and is a virtual means, that is, the line is not real, but the electric field of the object it reflects is real!

In this problem: A is false, it should be its direction of force, and its direction of motion is not affected by the initial velocity.

B is false, the straight electric field line can only reflect the same direction of the electric field at each point on the line, but cannot reflect the magnitude. The electric field line qualitatively reflects the magnitude of the field strength by the degree of density.

c False, if the field line is straight, the positive charge can move in a straight line along the field line, but if the field line is a curve, assume that it also moves along the curve, and we know that the electric field force is in the tangential direction, then what force provides the normal force necessary for it to make the curve? The answer is no, i.e. it is not possible to do such a motion only under the action of an electric field force.

dCorrect, the place where the line is not drawn does not indicate that there is no electric field, and the density of the two electric field lines near it qualitatively indicates the magnitude of the field strength here.

It's written in a bit wordy, and I hope you can understand it.

d right. A: The direction of force is the direction of the electric field line, such as the charge is fixed in the electric field, there is an electric field but no movement, B: The electric field line of the point charge is a straight line, but not a uniform electric field.

c. If the point charge is fixed in the electric field, the initial velocity = 0, but it cannot move in the direction of the electric field.

D drawing electric field lines is just a schematic illustration, and there is also an electric field in the space between the two electric field lines, so it is not necessarily correct that there is no electric field where the electric field lines are not drawn.

The direction of the electric field line is positive, not the direction of velocity, and a is wrong.

The intensity of the electric field is judged according to the density of the electric field lines, and has nothing to do with the shape of the electric field lines.

In the composite field, the charge moves along the line of the combined electric field, c is wrong.

The electric field line is a line that is artificially set and does not actually exist, d is correct.

The direction of movement of da is wrong, the electric field is large and small, and the direction is c, and the superposition of multiple electric fields is not the case.

First of all, it is necessary to understand and distinguish the conditions for objects to move in a straight line and in a curve, and not only to find conclusions from phenomena, which is not a good learning method.

Linear motion: the direction of the resultant external force is constant and the direction of the initial velocity of the object is the same as that of a straight line (or the initial velocity is zero) curvilinear motion: the direction of the resultant external force is different from the direction of the initial velocity, and the direction of the combined external force changes.

If the electric field line is a curve, then the electric field force on the charge is constantly changing, then the charge moves in a curve, but because the direction of the electric field force and the direction of the velocity are not in the same straight line, the trajectory of the charge movement cannot coincide with the electric field line, that is, the electric field line is not the trajectory of the charge at this time.

Conclusion: When the electric field line is a straight line, and the initial velocity of the charge is zero or the direction of the initial velocity is in the same straight line as the electric field line, the trajectory of the charge coincides with the electric field line.

The positive charge does not necessarily move in the direction of the electric field lines.

The electric field lines are not the trajectory of the charged particles, and when the direction of the electric field lines and the direction of motion of the charge are not in the same straight line, the trajectory of the charge is a curve.

Special case: The positive charge moves in the direction of the electric field line only if the electric field lines are in a straight line, the velocity direction of the positive charge is sumed, and the direction of the electric field lines is in the same straight line.

The electric field lines of the electrostatic field also have the following properties: (1) the electric field lines are not closed, starting from a positive charge or infinity and ending at infinity or a negative charge; [1] (2) the electric field lines are perpendicular to the surface of the conductor; (3) The electric field lines are perpendicular to the equipotential surface However, it should be noted that in general, the electric field lines are not orbits in which the positive charge is moved by the electric field force. Because the direction of the charge motion (i.e., the direction of velocity) is not necessarily in the direction of the force.

Electric field lines are not trajectories. Sometimes a positive charge moves along the electric field lines. When the electric field lines are straight lines, the direction of the initial velocity and the electric field lines are collinear, they will move along the electric field lines.

It can only be said that the force received by the positive charge in the electric field is in the direction of the electric field lines.

Answer: Electric field lines are not the trajectories of the point charge in an electric field.

The trajectory of charged particles is determined by two factors: the direction of initial velocity and the direction of force of charged particles, and only when the velocity direction of charged particle particles and the direction of force are in the same straight line, the trajectory of charged particles can be in the same straight line as the direction of force.

The electric field lines that meet this condition must be straight and the direction of velocity is parallel to the electric field lines, so the electric field lines are not the trajectory of the point charge in the electric field.

a. The tangent direction of any point on the electric field line is the direction of the field strength of the point, that is, the force direction of the positive charge is tested, but it is not necessarily the direction of movement of the charge, so a is wrong;

b. The tangent direction of the electric field line is different at different positions, so the direction of the electric field strength must change, so it must be a non-uniform electric field, and the electric field line is a straight line, indicating that the direction of the electric field strength is the same, but the size of the electric field strength depends on the distribution of the electric field line, so it cannot be affirmed that the uniform electric field beam is eliminated, so B is wrong;

c. The electric field force does not do work when the charge moves on the equipotential surface, that is, the direction of the electric field force is perpendicular to the equipotential surface when the charge moves on the equipotential surface, that is, the electric field lines must be perpendicular to the equipotential surface where it intersects, so C is correct;

d. The charge moves along the direction of the electric field line, one is the initial velocity is 0, and the other is the electric field along the straight line, which is the direction of the positive slag wheel of the charge movement to coincide with the electric field line, so d is wrong

Therefore, c

The trajectory is complex and can be discussed qualitatively.

The electric field line is bent, at this time, if a positive charge is released from rest in the electric field, regardless of gravity or anything, only the electric field force is considered, at the beginning the charge will move along the tangent direction of the point of the electric field line where it is located, and the acceleration direction is the same as the tangent direction, the next moment, the charge gains velocity, and will break away from the electric field line at the beginning, run to another electric field line, and at the same time receive a tangential electric field force, at this time, the acceleration direction and the velocity direction are not in the same direction. So the charge moves like a parabola.

If the trajectory of motion is depicted, then the velocity direction of the charge is along the tangent direction of the trajectory, and the direction of acceleration (or the direction of the electric field force, f=ma) is along the tangent direction of the electric field line.

The direction of velocity is the tangent direction of the curve. The direction of the charge movement depends on the force, not the tangential direction.

a. Where the electric field line is a straight line, it is not necessarily a uniform electric field, such as the electric field line of the point charge, so a is wrong

b. The direction of the electric field line is the direction of the electric field force experienced by the positive charge, which is opposite to the direction of the electric field force experienced by the negative charge, and it is not the direction of motion, so B is wrong

c. The electric field line does not necessarily coincide with the trajectory of the charged particle, only if the electric field line is a straight line, and the initial velocity of the charged particle is zero or the initial velocity direction is in the same straight line as the direction of the electric field line, the electric field line coincides with the trajectory of the charged particle, so c is correct

d. The density of the electric field line represents the strength of the electric field, so the denser the electric field line, the stronger the field strength, and the electric field line does not exist, which is hypothetical so D is wrong

Therefore, c

1. The charge does not have to move perpendicular to the electric field line.

2. The charge can accelerate and decelerate along the direction of the electric field line.

3. When the charge enters the electric field perpendicular with a certain initial velocity, the flat-like motion is completed only under the action of the electric field force.

4. The charge can also complete a uniform circular motion in an electric field.

a. The direction of the electric field line is the direction of the field strength at the point, which is the direction of the positive charge force, so a is wrong B. The positive charge does not necessarily move along the electric field line only under the action of the electric field force, and only moves along the electric field line when the electric field line is a straight line and the initial velocity is zero or the initial velocity is along the direction of the electric field line, so B is wrong

c. The denser the electric field line, the stronger the field, the greater the electric field force of the same charge here, so c is correct D. The electric field is an objective existence, and the electric field line is artificially virtual, not an objective existence, so d is wrong Therefore, c