Chapter 27: Magnetic Fields and Forces
Currents (moving charges) create magnetic fields. The familiar refrigerator magnetic has moving charges that create its magnetic field (electrons orbiting the nucleus of the atom), but we don't have a complete understanding of why different materials have different magnetic properties. In this chapter we won't worry about what creates the magnetic field and will focus instead on i.) describing magnetic fields (with field vectors, a compass, and field lines) and ii.) the effect of magnetic fields on charged particles (the Lorentz force). We will map magnetic field lines because that tells us about the forces between magnets (that like poles repel). Further, we will explore the force that a charged particle experiences in a magnetic field. This force depends not only on the magnitude of the magnetic field, but on the speed of the particle as well as its orientation in the magnetic field.
Table of Contents
Illustrations
- Illustration 27.1: Magnets and Compass Needles.
- Illustration 27.2: Earth's Magnetic Field.
- Illustration 27.3: A Mass Spectrometer.
- Illustration 27.4: Magnetic Forces on Currents.
- Illustration 27.5: Permanent Magnets and Ferromagnetism.
Explorations
- Exploration 27.1: Map Field Lines and Determine Forces.
- Exploration 27.2: Velocity Selector.
- Exploration 27.3: Mass Spectrometer.
Problems
- Problem 27.1: Identify the poles of a square magnet.
- Problem 27.2: Identify field-line diagram.
- Problem 27.3: Identify correct trajectory of particle moving through a magnetic field.
- Problem 27.4: Force on moving charges in a current carrying wire: find the direction of the field.
- Problem 27.5: Force on current carrying wire.
- Problem 27.6: Rank magnetic fields that an electron moves through.
- Problem 27.7: Rank charges as they move through magnetic field.
- Problem 27.8: Mass spectrometer.
- Problem 27.9: Velocity selector.
- Problem 27.10: Find the mass of the current carrying rod in a magnetic field.
