电场问题,电场是背景,核心是带电粒子的运动.在诸多电场问题中,有一类问题具有相似的特性,这类问题中有些物理量不管背景如何,它们的变化规律是确定的,而有些物理量则因为背景的不同而出现不同的变化情况,变得极其不确定.1仅有运动轨迹问题中的确定与不确定例1已知电荷在电场中划过的轨迹为曲线ab,图1中只画出电场线的疏密,并没有标出电场线的方 The electric field problem is the background of the electric field and the core is the movement of charged particles. One of the many electric field problems has similar characteristics. Some of the physical quantities of these kinds of problems are definite regardless of the background, while some of the physical quantities Due to different backgrounds, different changes occur and become extremely uncertain.1 Only the determination and uncertainty in the motion trajectory problem Example 1 It is known that the trajectory of the electric charge in the electric field is a curve ab, and only the The density of the electric field lines, and did not mark the side of the electric field lines