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Physics Lesson Plan Teacher Howard Unit Title Length Goal(s)/PLO(s): Course Grade Level Block/Period Phys 12 12 L1 analyse electromagnetism, with reference to magnetic fields and their effects on moving charges state the rules explaining how magnetic poles interact with each other describe and illustrate the direction of the magnetic field lines for a permanent magnet use the right-hand rule to determine the magnetic field direction for a current-carrying wire or a solenoid Date Class Size Lesson #, of 20-04 determine the direction of the force exerted on a current-carrying conductor or a moving charge that is within a magnetic field solve problems that deal with a currentcarrying conductor placed in a magnetic field and that involve – magnetic force – current – length of conductor in the field – magnetic field Materials: Magnets, compasses Timeline Class Activities Introduction Body Notes 20-04 to 20-06 Closure Questions 8-24, Problems 9-23 odd 20-04 Force on Electric Charge Moving in a Magnetic Field Freely moving charges are analogous to current flowing through a wire so moving electric charges experience a force in a magnetic field. If N charged particles pass by a given point in time t then they have a current: If t is the time for a charge q to travel a distance l in a magnetic field: where v is the velocity of the particles or for one particle moving perpendicular to the magnetic field The direction of the force is again given by a right hand rule: The 3rd Right Hand Rule If the pointer finger of your right hand points in the direction of the (+) particle’s velocity v, and the middle finger points in the direction of the magnetic field B, then the thumb points in the direction of force. Example 20-3, 20-4 The path of a charged particle moving in a plane perpendicular to a uniform magnetic field is in a circle. http://www.regentsprep.org/Regents/physics/phys03/cdeflecte/defa ult.htm The force is always perpendicular to v so the magnitude of v does not change and the particle experiences an acceleration: Example 20-5 Vector cross products • if you have an expression like you are multiplying 2 vectors together to get a third. • the right hand rule equivalent is Thumb=Pointer X Middle 20-5 Magnetic field Due to a Long Straight Wire The magnetic field B is proportional to the current I in the wire and inversely proportional to the distance r from the wire as long as r is much less than the length of the wire. where µ 0 is the permeability of free space Questions 8-24 Problems 9-23 odd