Although electric field is tangent to electric field lines, free charged particles do not necessarily move alone the field lines. Explain why not, and give a specific example illustrating your reasoning

The direction of electric field is always tangential to field lines. However, free charged particles do not necessarily move alone the field lines. Curved field lines means that there is a continuous change of force on the charge and thus, its direction of acceleration would change accordingly. Moreover, if the charge is negative it is bound to move opposite to the field direction. Hence, we can say that although electric field is tangent to electric field lines, free charged particles do not necessarily move alone the field lines.