Magnetism (sec. 27.1) Magnetic field (sec. 27.2) Magnetic field lines and magnetic flux (sec. 27.3) Motion of charges in a B field (sec. 27.4) Applications

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  • Slide 1
  • Magnetism (sec. 27.1) Magnetic field (sec. 27.2) Magnetic field lines and magnetic flux (sec. 27.3) Motion of charges in a B field (sec. 27.4) Applications - moving charged particles (sec. 27.5) Magnetic force on conductor with current (sec. 27.6) Force and torque on a current loop (sec. 27.7) Direct current motor(sec. 27.8) The Hall effect(sec. 27.9) Magnetic Field & Forces Ch. 27 C 2009 J. Becker
  • Slide 2
  • Forces between bar magnets (or permanent magnets )
  • Slide 3
  • Earths magnetic field (Note the N-S polls of magnet!)
  • Slide 4
  • Compass over a horizontal current-carrying wire
  • Slide 5
  • Magnetic force acting on a moving (+) charge
  • Slide 6
  • Magnetic field lines associated with a permanent magnet, coil, iron-core electromagnet, current in wire, current loop
  • Slide 7
  • MAGNETIC FLUX through an area element dA
  • Slide 8
  • Orbit of a charged particle in a uniform magnetic field is a circle R = m v / q B
  • Slide 9
  • The Van Allen radiation belts around the Earth
  • Slide 10
  • Velocity selector for charged particles uses perpendicular E and B fields q v B = q E v = E / B
  • Slide 11
  • Mass spectrometer uses a velocity selector to produce particles with uniform speed. And from R = m v / q B we get q / m = v / B R
  • Slide 12
  • Force on a moving positive charge in a current-carrying conductor: F = I L x B L I I For vector direction use RIGHT HAND RULE
  • Slide 13
  • Magnetic force on a straight wire carrying current I in a magnetic field B Right hand rule F = I L x B
  • Slide 14
  • Magnetic field B, length L, and force F vectors for a straight wire carrying a current I
  • Slide 15
  • Components of a loudspeaker F = I l x B
  • Slide 16
  • Forces on the sides of a current-carrying loop in a uniform magnetic field. This is how a motor works!
  • Slide 17
  • Right hand rule determines the direction of the magnetic moment ( ) of a current-carrying loop
  • Slide 18
  • Torque ( x B) on this solenoid in a uniform magnetic field is into the screen thus rotating the solenoid clockwise
  • Slide 19
  • Current loops in a non-uniform B field
  • Slide 20
  • Atomic magnetic moments in an iron bar (a) unmagnetized (b) magnetized (c)Torgue on a bar magnet in a B field
  • Slide 21
  • Bar magnet attracts an unmagnetized piece of iron; the B field gives rise to a net magnetic moment in the object
  • Slide 22
  • A simple DC motor
  • Slide 23
  • The Hall effect forces on charge carriers in a conductor in a B field. With a simple voltage measurement we can determine whether the charge carriers are positive or negative.
  • Slide 24
  • A linear motor
  • Slide 25
  • Electromagnetic pump
  • Slide 26
  • See www.physics.edu/becker/physics51 Review C 2009 J. F. Becker