University:
Texas State University
Course:
PHYS 1310 | Elementary Physics I.
Academic year:

2022
Views:

436

Pages:

3
Author:

Malcolm Li

Magnetism Notes & Summary 1. Magnets and Magnetic Fields Magnets:    Magnets attract iron-containing objects. Magnets have two distinct poles called the north pole and the south pole. These names are derived from a magnet’s behavior on Earth. Like poles of magnets repel each other; unlike poles attract each other. Magnetic Domains:     A region composed of a group of atoms whose magnetic fields are aligned in the same direction is called a magnetic domain. Some materials can be made into permanent magnets. Soft magnetic materials (for example iron) are easily magnetized but tend to lose their magnetism easily. Hard magnetic materials (for example nickel) tend to retain their magnetism. Magnetic Fields:      A magnetic field is a region in which a magnetic force can be detected. Magnetic field lines can be drawn with the aid of a compass. Earth’s magnetic field is similar to that of a bar magnet. The magnetic south pole is near the Geographic North Pole. The magnetic north pole is near the Geographic South Pole. Magnetic declination is a measure of the difference between true north and north indicated by a compass. 2. Magnetism from Electricity Magnetic Field of a Current-Carrying Wire:    A long, straight, current-carrying wire has a cylindrical magnetic field. Compasses can be used to shown the direction of the magnetic field induced by the wire. The right-hand rule can be used to determine the direction of the magnetic field in a current-carrying wire. Magnetic Field of a Current Loop:   Solenoids produce a strong magnetic field by combining several loops. A solenoid is a long, helically wound coil of insulated wire. 3. Magnetic Force Charged Particles in a Magnetic Field:  A charge moving through a magnetic field experiences a force proportional to the charge, velocity, and the magnetic field.  The direction of the magnetic force on a moving charge is always perpendicular to both the magnetic field and the velocity of the charge. An alternative right-hand rule can be used to find the direction of the magnetic force. A charge moving through a magnetic field follows a circular path.   Magnetic Force on a Current-Carrying Conductor:   A current-carrying wire in an external magnetic field undergoes a magnetic force. The force on a current-carrying conductor perpendicular to a magnetic field is given by: Fmagnetic = B x I x L magnitude of magnetic force = (magnitude of magnetic field)  (current)  (length of conductor within B)     Two parallel current-carrying wires exert a force on one another that are equal in magnitude and opposite in direction. If the currents are in the same direction, the two wires attract one another. If the currents are in opposite direction, the wires repel one another. Loudspeakers use magnetic force to produce sound.