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COLLEGE PHYSICS, PHYS 104
Behavioral Objectives
Unit III(a)
C
1.
In relation to magnetism, be able to:
a.
b.
c.
d.
e.
f.
g.
h.
C
2.
identify its origin in the atom.
apply the principles of the domain theory to solve
a practical situational problem.
identify its electrical origin.
apply the law of poles to solve a practical
situation.
identify the properties of and draw sketches for
magnetic field lines between magnet combinations.
identify the origin properties of, and effects
caused by the earth’s magnetic field.
identify the nature of the electromagnetic force
field surrounding a stationary charge; moving
charge plus the origin of each field.
identify the physical principles involved which
distinguish magnetic from non-magnetic materials.
For the magnetic force on a current-carrying wire
(conductor) be able to:
a.
b.
c.
d.
E
e.
E
f.
C - concepts
apply the right-hand rule (for positive charges)
to find the direction of the force (rotation of a
wire), current and/or magnetic field vector in
terms of the other two variables.
identify practical devices used which apply this
principle, i.e., motor and the basic principles of
their operation.
identify the effect on the magnetic field, B,
caused by increasing the number of turns of wire,
increasing the current, reversing the current’s
direction and adding iron into the coil’s core.
apply to meter movement to explain the basic
principles of operation of a galvanometer.
solve for the force (direction also) acting on a
wire of known length carrying known current in a
given magnetic field direction.
using appropriate equations, solve for the:
magnetic field, B, at a given distance from a
long, straight wire, and interior of a coil and
solenoid using current, turns of wire and/or
distance in terms of the other variables.
E - equations used
E
g.
E
h.
i.
-2solve for the magnetic field, B,(including
direction), at a given distance from two wires
carrying known current in a given direction.
Solve for the force (direction also) acting on two
parallel (and perpendicular) wires, particle
beam,(given charge) or a wire of known length plus
current and magnetic field (with direction) at a
given distance apart (and charge’s velocity).
use the right-hand rule to find the direction of
the magnetic field, B, around a straight current
wire and current loop whose current direction is
known.
C
3.
For a charged particle moving in a magnetic field, be
able to:
a.
b.
c.
d.
e.
C
4.
E
apply the right hand rule for positive charges to
find the direction of the force, particle, and/or
magnetic field in terms of the other two.
apply the results of (a) to explain phenomena such
as cathode ray tube, mass spectrometer, magnetic
bottle, etc.
solve for mass, speed, charge, B field, or radius
of curvature in terms of the others.
solve for the force (direction also), charge,
speed, or magnetic field strength in terms of the
others for a moving particle in a magnetic field.
solve for the speed, electric field, charge, or
magnetic field in terms of the others.
For the torque for a current loop in a known magnetic
field direction, solve for the:
a.
the direction of rotation using right-hand rule.
b.
torque on a current loop, area (calculate from
radius or sides), no. of turns, magnetic field,
current or angle in terms of the other variables.
LABORATORY OBJECTIVES - WEEK 1
Magnetic Induction, Magnets and Electromagnets
1.
For magnets and electromagnets, be able to:
a.
b.
c.
d.
apply the law of poles to solve a practical situation.
identify the direction and draw in magnetic field lines
for two magnets placed nearby.
identify the effect of hitting an iron rod with a
hammer in different directions.
Using a gilley coil set-up which you have properly
connected yourself, identify the direction of the
magnetic field; role of an iron core inserted into the
coil on the magnetic field.
e.
2.
-3using the set-up in (d) and a compass needle, identify
the effect of increasing the current or strength of the
magnetic field produced by the coil, e.g. attraction of
a compass needle.
In relation to magnetic induction, be able to identify and
explain the physical principles for a practical situation:
a.
b.
c.
d.
materials which are magnetic and those that are nonmagnetic.
whether iron or steel can be magnetized permanently.
the effect of distance of a magnet on the strength of
induced poles.
materials which act as a shield from magnetism.
Learning Activities for Magnetism:
Read:
Textbook, College Physics, 9th ed, Serway/Vuille, Chapter 19
College Physics (Schaum’s Outline), pps. 298-313, 324.
Optional:
Conceptual Physics, pps. 458-473 in the 10th ed. (pps. 458474 in 9th ed) both on reserve in Library.
Homework:
Chapter 19 M-C Q’s(show calculations for each) 2, 3, 11 & 15;
Concept Q’s 6 and 12
Problems: 3, 12, 18, 25, 33, 36, 41*, 44, 48(a),(b); 50*, 60, 69
and Extra (not starred or worth extra credit)
1.
The parallel wires in a lamp cord are 2.0 mm apart. What is
the force per meter between them when the cord is used to supply
power to a 120 V, 200 W light bulb? Current flows in opposite
directions in each wire.
2.
An electron enters a region of a magnetic field of magnitude
0.010 T, traveling perpendicular to the boundary of the region.
The direction of the field is perpendicular to the electron’s
velocity. Find the time it takes the electron to leave this
region if it travels in a semicircular path.
Exercises on Magnetism (handout) see next page.
Answers to Selected Even-Numbered Exercises:
18(a)9 x 10-3 N @ 150 above horizontal toward the North,(b)2.3 x 10-3 N
horizontal to West
36. 0.150 mm
44(a) left (b)out (c)lower left to upper right
48(a) 40.0 µT into (b) 5.00 µT out
60. 4.8 x 104 turns
-4
Extra 1. 2.78 x 10 N/m repulsion
Extra 2: 1.79 ns
Good Websites:
www.ionaphysics.org/lab/Demoes.htm - magnetic fields, charged
particle in magnetic field, electric motor, etc
www.walter-fendt.de/ph14e/index.html - Direct Current Electric
Motor, Magnetic Fields, etc.
-4A-V Materials:
Video:
Magnetism in Space (20 minutes)
Laboratory:
Magnets and Electromagnets (12)
Exercises On Magnetism
1.
2.
3.
Since every iron atom is a tiny magnet, why are not all iron
materials themselves magnets?
Why will a magnet attract an ordinary nail or paper clip,
but not a wooden pencil?
If a bar magnet is carefully broken in half as shown in
Figure 1, each piece will be an equally strong magnet. If
the magnet is carefully broken in half along its long axis,
how would the strengths of the pieces compare to that of the
original magnet? Justify your answer using physics
principles.
Figure 1.
4.
Why will a magnet placed in front of a television picture
tube distort the picture? (NOTE: Do NOT try this with a
color set. If you succeed in magnetizing the metal mask in
back of the glass screen, you will have picture distortion
even when the magnet is removed!).
5.
Magnet A has twice the magnetic field strength of magnet B,
and at a certain distance pulls on magnet B with a force of
20 pounds. With how much force, then, does magnet B pull on
magnet A? Justify using physics principles.
6.
A cyclotron is a device for accelerating charged particles
in ever-increasing circular orbits to high speeds. The
charged particles are subjected to both an electric field
and a magnetic field. One of these fields increases the
speed of the charged particles and the other field holds
them in a circular path. Which field performs which
function? Explain using physics principles.