Phys 115 1st Edition Lecture 13Outline of Last Lecture I. CapacitanceOutline of Current Lecture II. MagnetismIII. Torque on magnetic dipole due to a magnetic fieldIV. Magnetic force on charged particlesCurrent Lecture- A magnet that is free to rotate will rotate when another magnet is brought near.- We say there is a magnetic force between the two magnets.- A magnet experiences a magnetic force whenever it is in the magnetic field of another magnet.- Earth has a magnetic field. We call the end of a magnet that points north the north pole of the magnet, and the end that points south the south pole of the magnet.- All magnets are dipoles: They have a north and a south pole.- Like poles repel and opposite poles attract.- Magnetic field lines point from the magnet’s north pole to its south pole.- Magnetic field lines exist inside the magnet; they do NOT stop at the poles.- The magnetic dipole moment is a vector that points from the south pole of a magnet toward its north pole.- When a magnet is placed in an external magnetic field of magnitude B, the field exerts a torque on the magnet of magnitude- The torque causes the magnet to rotate.- What direction will the magnet rotate?o Point your fingers in the direction of and curl them toward the direction points.o The direction your fingers curl determines the direction the magnet rotates.- Only certain types of materials (called ferromagnetic materials) can become permanent magnets or are attracted to magnets.- A ferromagnetic object will become a permanent magnet if the magnetic dipole moments of its atoms are aligned.- A charged particle moving at a speed v in a magnetic field of magnitude B experiences a magnetic force.- Acceleration is the rate of change of velocity with time.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Velocity is a vector, so it has a magnitude (called “speed”) and a direction.- An object experiences an acceleration (i.e., a change in velocity) if its speed changes AND/OR its direction changes.- When an object is moving in a circle, the direction it is moving is constantly changing.- The acceleration that causes this change in direction is called “centripetal acceleration.”- If the object has a speed v and is moving on a circular path, then centripetal accelerationhas a magnitude v2/r.- Centripetal acceleration always points toward the center of the
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