Solution

Statement

$7.1.1.$ In what case does a charged particle in an electric field move along the electric field lines?

Solution

Electric field lines indicate the direction of the force acting on a positive charge. If the initial velocity of the particle coincides with this direction and there are no other external influences, the motion will occur strictly along the field line.

For a positive charge, the motion will be in the direction of the field line; for a negative charge, it will be opposite to the direction of the field line. It is important to note that this is only possible if the field line is perfectly straight, otherwise, the particle's inertia would cause it to deviate from a curved path.