Download PHY 231 Lecture 29 (Fall 2006)

0
Physics 213
General Physics
Lecture 8
Last Meeting: Kirchhoff Rules, RC
Circuit
Today: Magnetism & Magnetic
Field
2
3
Magnetic Resonance Imaging
(MRI)
Maglev Train
Examples of Other Magnetic Field Applications

Demo

Magnetic Materials, Magnets
 Dip Meter
 Attraction and Repulsion
7
8
Demo: iron filings
9
Magnetic Field Lines, sketch
A compass can be used to show the direction of
the magnetic field lines (a)
A sketch of the magnetic field lines (b)
Magnetic Field Lines, Similar to
Electric Dipole
Magnetic Dipole
Electric Dipole
12
13
14
Earth’s Magnetic Field
The Earth’s magnetic
field resembles that
achieved by burying
a huge bar magnet
deep in the Earth’s
interior
A Few Typical B Values
Conventional laboratory magnets
25000 G or 2.5 T
Superconducting magnets
300000 G or 30 T
Earth’s magnetic field
0.5 G or 5 x 10-5 T
Crookes Tube
17
18
19
Determining the Direction of
Force, the Right Hand Rule
Point your fingers in the
direction of v
Curl the fingers in the
direction of the magnetic
field, B
Your thumb points in the
direction of the force, F , on
a positive charge
If the charge is negative, the
force is opposite that
determined by the right hand
rule
Right Hand Rule Examples
F
.
v
F
-e
v
-e
B
B
Velocity out of
page.
Velocity into
page.
22
23
Q3
24
25