Particle Trajectory in a Straight Boundary Magnetic Field

This applet demonstrates the geometric model of a charged particle moving in a uniform magnetic field with a straight boundary. By constructing the boundary line, entry and exit points, and the circular arc of the trajectory, it visually illustrates the geometric characteristics of the particle's uniform circular motion. Using geometric objects such as circles, segments, orthogonal lines, and vectors, it precisely depicts the perpendicular relationships between the trajectory center, radius, and velocity direction, helping students understand critical problems and geometric construction methods for particle motion in magnetic fields. Users can interactively drag the entry point along the boundary to observe how the trajectory changes. As the entry position varies, the radius of curvature, the exit point, and the deflection angle all update in real time, allowing learners to explore the relationship between the magnetic field strength, particle velocity, and the resulting circular path. The applet highlights key geometric properties, including the fact that the velocity vector is always tangent to the circular arc, the radius is perpendicular to the velocity at every point, and the center of the circular trajectory lies on the perpendicular line drawn from the entry point. This visual and dynamic representation makes it easier for students to grasp the underlying physics and geometry without relying solely on abstract formulas. It is particularly useful for studying critical angle problems, minimum magnetic field requirements, and the conditions under which particles enter or exit the field region.