The path of a moving charged particle in a magnetic field is ………

The path of a moving charged particle in a magnetic field is circular or helical.

Here's why:

1. When a charged particle enters a magnetic field perpendicularly, it experiences a magnetic force that is always perpendicular to the direction of its motion. This force changes the direction of the particle's velocity vector but not its magnitude, causing the particle to move in a circular path.

2. If the particle enters the magnetic field at an angle, its motion will be a combination of a circular path in the plane perpendicular to the field and a linear motion parallel to the field. This results in a helical path.

3. The direction of the force (and therefore the direction of the circular motion) is given by the right-hand rule. If you point your thumb in the direction of the particle's velocity and your fingers in the direction of the magnetic field, your palm will point in the direction of the force (for a positively charged particle).

4. The radius of the circular path depends on the charge and speed of the particle and the strength of the magnetic field. The faster the particle or the stronger the field, the smaller the radius. The larger the charge, the smaller the radius.

5. The pitch of the helix (the distance between turns) depends on the component of the particle's velocity parallel to the field. The greater this component, the greater the pitch.