Question

Which of the following particles will experience the maximum magnetic force (magnitude) when projected with the same velocity perpendicular to the magnetic field?

• A. Electron
• B. Proton
• C. He+
• D. Li++

Answer 1

Answer: (D)

Li++

Answer 2

The magnetic force on a charged particle moving in a magnetic field is given by the Lorentz force law:
$F=qvBsinθ$
where q is the charge of the particle, v is its velocity, B is the magnetic field strength, and θ is the angle between the velocity and the magnetic field. Since all particles are moving perpendicular to the magnetic field, sinθ=1, so the force is directly proportional to the charge of the particle.
Electron: charge = −e; Proton: charge = +e; He+ (Helium ion): charge = +e (since it’s lost one electron); Li++ (Lithium ion): charge = +2e (since it has lost two electrons).
The particle with the largest charge will experience the greatest force. Since Li++ has a charge of +2e, it will experience the maximum force.