Summary
The force on a moving charge in a magnetic field is determined by the equation F = BQv sinθ, where the force is perpendicular to both the velocity and the magnetic field, causing circular motion. The Hall voltage is a potential difference across a conductor due to the Hall effect, used to measure magnetic flux density with a Hall probe. A velocity selector uses electric and magnetic fields to filter particles by velocity.
Exam Tips
Key Definitions to Remember
- Magnetic Force on a Moving Charge — The force experienced by a charge moving in a magnetic field, calculated as F = BQv sinθ.
- Hall Voltage — The potential difference across a conductor when a magnetic field is applied perpendicular to the current.
- Velocity Selector — A device that uses perpendicular electric and magnetic fields to filter particles of a specific velocity.
Common Confusions
- Confusing the direction of force with the direction of velocity.
- Misunderstanding the role of the angle θ in the force equation.
Typical Exam Questions
- How do you calculate the force on a charge moving in a magnetic field? Use F = BQv sinθ, considering the angle between velocity and field.
- What is the Hall voltage and how is it generated? It's the potential difference across a conductor due to the Hall effect.
- How does a velocity selector work? It filters particles by balancing electric and magnetic forces.
What Examiners Usually Test
- Application of Fleming’s Left-hand Rule to determine force direction.
- Calculation of force on a moving charge using F = BQv sinθ.
- Understanding of how Hall voltage is used to measure magnetic flux density.
