Motion in a Magnetic Field – Class 12 | Chapter – 4 | Physics Short Notes Series PDF for NEET & JEE

Motion in a Magnetic Field: The motion of a charged particle in a magnetic field is determined by the interplay between the magnetic force acting on the particle and any other forces that may be present. The motion of charged particles in magnetic fields is important in many technological applications, such as in particle accelerators, where charged particles are accelerated to high speeds by magnetic fields, and in mass spectrometers, where magnetic fields are used to separate ions based on their mass-to-charge ratio.

Motion in a Magnetic Field

If a charged particle is moving with velocity “v” in a magnetic field “B,” it experiences a force “F” given by:

F = q × v × B

where q is the charge of the particle. This force is perpendicular to both the velocity and the magnetic field, and it causes the particle to move in a circular path. The radius of the circular path is determined by the strength of the magnetic field and the velocity of the particle.

If the charged particle is moving at a constant speed, the magnetic force provides the centripetal force needed to keep the particle moving in a circular path. If the particle is moving in a straight line, the magnetic force will cause it to bend in a circular path.

In certain cases, a charged particle moving in a magnetic field may also experience a force parallel to the magnetic field. This occurs if the velocity of the particle is not perpendicular to the magnetic field, or if there is an electric field present in addition to the magnetic field.

Properties of Motion in a Magnetic Field

The properties of motion in a magnetic field can be summarized as follows:

  • Path: The path of a charged particle in a magnetic field is a circle or a helix, depending on the relative orientation of the velocity and the magnetic field.
  • Speed: The speed of the charged particle is constant along its path, as long as there are no other forces acting on it.
  • Direction: The direction of motion of the charged particle changes continuously as it moves along its path, due to the perpendicular nature of the magnetic force.
  • Radius: The radius of the path is determined by the strength of the magnetic field and the velocity of the charged particle, and it is inversely proportional to the strength of the magnetic field.
  • Centripetal force: The magnetic force provides the centripetal force that keeps the charged particle moving in a circular path.
  • Stability: The charged particle is in a stable state in a uniform magnetic field, as long as no other forces are acting.
  • Helix: If the charged particle is moving at an angle to the magnetic field, its path will be a helix, with the radius of the helix determined by the relative orientation of the velocity and the magnetic field.
  • Cyclotron frequency: The charged particle moves with a constant frequency around its path, known as the cyclotron frequency, which depends on the strength of the magnetic field and the charge of the particle.
  • Motion in combined fields: The motion of a charged particle in a combined electric and magnetic field is more complex and depends on the relative strengths and orientations of the fields.


JOIN OUR TELEGRAM CHANNELS
Biology Quiz & Notes Physics Quiz & Notes Chemistry Quiz & Notes

Follow on Facebook

By Team Learning Mantras