Magnetic Force on a Point Charge

🔖 Topics

Derive the expression for the radius of a particle traveling in uniform circular motion in a magnetic field
Analyze the motion of charged particles in a mass spectrometer
Analyze the motion of charged particles in a velocity selector
Become more comfortable with the right-hand rule for a charged particle in a magnetic field

Magnetic force on a point charge
Uniform circular motion of a charged particle in a magnetic field
- Derivation of the radius of the circular motion
Mass spectrometer
Velocity selector

An ion with a charge of +2.5 mC and an unknown mass moves in a circle of radius 12.5 cm when inside a magnetic field of 1.2 T. If the speed of the ion is 100 m/s, what is the mass of the ion?
A uniform magnetic field points vertically upward with a strength of 0.5 T. An electron with kinetic energy \( 2.5 \times 10^{-18} \: J \) is moving horizontally in this field. What is the magnetic force acting on the electron? The mass of an electron is \( 9.11 \times 10^{-31} \: kg \) and the charge on an electron is \( 1.6 \times 10^{-19} \: C \).
A particle with a charge of 0.5 mC is moving with a velocity of 25 m/s in the \( +\hat{x} \) direction. If the magnetic field around the particle is 20 mT in the \( -\hat{y} \) direction, what is the magnetic force on the particle (magnitude and direction)?
A particle with a charge of -1.7 mC is moving with a velocity of 32 m/s in the \( -\hat{z} \) direction. If the magnetic field around the particle is 5 mT in the \( +\hat{y} \) direction, what is the magnetic force on the particle (magnitude and direction)?

Duffy, Andrew. “Mass Spectrometer.” Mass Spectrometer, https://physics.bu.edu/~duffy/HTML5/mass_spectrometer.html, January 2018.
Giambattista, Alan, et al. College Physics With an Integrated Approach to Forces and Kinematics. 5th ed., McGraw-Hill Education, 2020.