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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