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Second Term Paper – Science Fact or Cinematic Fiction?
Due Wednesday, November 17th (Next week)
100 points (50 points if late)
Homework #11 – Building a Scene in Maya
Due Wednesday, November 24th (Day before Thanksgiving)
20 points (10 points if late)
For full schedule, visit course website:
ArtPhysics123.pbworks.com
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Survey Question
How much experience do you have
using AutoDesk Maya?
A)
B)
C)
D)
A lot of experience
A little experience
Never used it but know of it
Not familiar with it at all
Review Question
Which of these is not a
mechanism for heat transfer?
A) Conduction
B) Radiation
C) Reduction
D) Convection
Heat Transfer
C) Reduction
Radiation
Convection
Conduction
Review Question
Fill in the blanks:
+
+
Two objects with positive charge _______
each other and two objects with negative
charge _______ each other.
A) Attract … Repel
B) Repel … Attract
C) Attract … Attract
D) Repel … Repel
-
-
Electric Charges and Forces
D) Repel … Repel
Like charges repel, opposite charges attract.
REPEL
REPEL
ATTRACT
Note that by Action/Reaction, the force on each object
is always equal in magnitude, opposite in direction.
Review Question
Flowing electrons strike atoms in a
conductor, heating the material.
This type of heating is named after:
A) André-Marie Ampère
B) Nicola Tesla
C) Thomas Edison
D) Georg Ohm
E) Alessandro Volta
Toaster
Ohmic Heating
Georg Simon Ohm (1789 –1854) was a
German physicist. As a high school
teacher, Ohm began his research with
the recently invented electrochemical
cell, invented by Italian Count
Alessandro Volta.
Georg Ohm
Using equipment of his own creation,
Ohm determined that there is a direct
proportionality between the potential
difference (voltage) applied across a
conductor and the resultant electric
current – now known as Ohm's law.
Ohmic heating is also called Joule heating,
first studied by James Prescott Joule in 1841
Effects Animation:
Electricity &
Magnetism
Part 2
WARNING
Strong magnets will be
passed around the room.
Keep these magnets away
from iPods and laptops
(especially my laptop)!
Electrocution
Electrocution
(death by electric
shock) is usually
due to ohmic
heating of the
internal organs of
the body.
True or False
Electrocution
False
It is due to the
disruption of the
nervous system,
especially that
which controls the
heart beat.
Nervous System
Nervous systems in animals use
electrical currents to signal the
contraction and relaxation of
muscles.
Frog leg jumps when
electrical current
passes through it.
Presto (2008)
Common visual gag is the
uncontrollable twitching
of a person’s muscles.
Notice
Jacob’s
Ladder
in Presto’s
hair
http://www.youtube.com/watch?v=mw-fs19kTGM
Sherlock Holmes (2009)
The electric shock does not exert a
force, rather it causes muscles to
contract; this scene is not realistic.
Conduction in Human Heart
The most important
electrical signal in our
body is the periodic
signal that contracts
and relaxes our heart
muscle to pump blood.
Without a constant flow
of blood the brain can
suffer permanent
damage.
SA
AV
Electric Shock
The damaging effects of shock are the result of
electrical current passing through the body.
Current depends on
the voltage and on
electrical resistance.
When dry, skin’s
resistance around
100,000 .
Resistance drops as
low as 100  when
wet and salty.
Effects of Electric Shock on Human Body
Current (A)
Effect
0.001
Can be felt
0.005
Is painful
0.010
Causes involuntary muscle
contractions (spasms)
0.015
Causes loss of muscle control
0.070
If through the heart, serious
disruption; probably fatal if
current lasts for more than 1 s
Frankenstein (1931)
Electricity brings
Frankenstein’s
monster to life in
the 1931 horror
classic yet it’s not
mentioned in the
original book,
written in 1818 by
Mary Shelley.
Bolts for
electrical
contact
http://www.youtube.com/watch?v=8H3dFh6GA-A
Magneto
http://www.youtube.com/watch?v=rKc4BWvWtuM
Magneto, the villain in the
X-men movies, controls
the force of magnetism.
The majority of the animation and
lighting in this scene was done in Maya.
Magnetic Forces
General observations regarding magnets:
Iron (and a few other metals) are
ferromagnetic, which means they can
become magnetized.
Magnets attract ferromagnetic metals.
Two magnets can either attract or repel
each other depending on poles.
Iron Ore
Ferromagnetic Metals
Ferromagnetic metals have similar atomic
structure.
Spin of the
electron in
these metals
produces a
net magnetic
field
Iron, Cobalt, Nickel
Many ferromagnetic alloys (blends of metals)
Demo: Magnetism & Money
Most US coins are not made of ferromagnetic materials
but many other countries use iron steel in their currency.
Some pennies
were made of
steel during
World War
II
Iron is in the ink used in US paper
currency to avoid counterfeiting.
Some Euro
coins contain
steel
Buffalo nickels
are 25% nickel
metal, which is
ferromagnetic
Magnetizing Iron
Magnetic domains can be induced to align
by an external magnetic field.
S
NS
Strong
Magnet
Strong
Magnet
N
N
Demo: Magnetizing Iron
Magnetic domains in iron nails are
induced to align by proximity of
the strong magnet
Each nail becomes itself a magnet,
which in turn magnetizes the
nail below it, forming a chain.
When the strong magnet is
removed, most of the domains
un-align and nail lose most of
their magnetization.
Demo: Demagnetizing Iron
Iron nail is attracted
to the large magnet
due to alignment of
domains in the nail.
Heat the nail to a high
temperature and the
domains become
randomized so the nail
is no longer attracted
to the magnet.
Magnets & Wile E. Coyote
Wile E. Coyote is surprised when a big metal can
of TNT comes flying in, pulled in by his magnet.
In reality, the force of the
can on the magnet is just as
strong as the pull of the
magnet is on the can of TNT.
True or False?
Magnets & Wile E. Coyote
True.
Another example of
action/reaction principle
(Newton’s Third Law).
Action force is magnet
pulling TNT can.
Reaction force is TNT can
pulling magnet.
From “Zipping Along”
Demo: Electromagnets
Electromagnet
created by passing
current through a
coil of wire.
Electromagnet is
stronger when an
iron bar is
inserted within
the coil.
N
Wire
Coil
S
Connect to
battery or
power supply
Iron Bar
Loudspeakers
Loudspeaker has a membrane but
oscillations are created by
variations in electrical current,
which cause an electromagnet to be
pulled towards and away from a
second, permanent magnet.
These oscillations cause the
membrane of the loudspeaker
to vibrate with the same
frequency as the oscillations in
the electrical current.
Headphones work
essentially the same way,
they’re just smaller.
The magnetic South pole is
near the geographic North
pole (so North pole of
compass attracted towards
Northern direction).
There isn’t an giant
underground magnetized
chunk of iron; Earth’s
interior is simply too hot.
N
The configuration of the
Earth's magnetic field
resembles a strong bar
magnet located near the
center of the Earth.
S
Earth’s Magnetic Field
Origin of Earth’s Magnetic Field
Earth is an electromagnet with electric currents
deep below the surface.
Moving charges, looping around within the molten
part of the Earth, create the magnetic field.
These currents are
possibly the result of
thermal convection
rising from the central
core combined with
the rotation of the
Earth about its axis.
Demo: Electric Motor
Can create an electrical motor by passing a
current through a set of electromagnets mounted on a rotating shaft.
Current out
Current in
Electro-magnets
Electric Motor, Analyzed
Electromagnet
mounted on a
shaft with
opposing magnets
on each side.
Current direction
always such that
electromagnet is
repelled, causing
shaft to turn.
Current
N
S
Current
N
S
Demo: Magnetic Force & Current
Moving charges in an electric current
experience a force due to magnetic field.
Demo: Crooke’s Tube
Electron beam in a Crooke’s tube is deflected
when a magnet is brought near the tube.
Television Tube
Electron beams, deflected by magnetic
fields, are used to create TV images.
Electromagnets
25-May-17
Demo: Magnets & TV sets
Picture on a TV set is distorted by presence of a
magnet since picture formed by an electron beam.
Warning: Strong
magnets can
permanently
damage a
television or a
computer.
Demo: Magnet Induces Current
Voltage and current are induced when a magnet
moves towards or away from a coil of wire.
Faster the magnet’s motion, the greater the
induced current.
Demo: Electric Generator
Turn the shaft
by hand and as
the coils pass
the magnets a
voltage is
induced.
DC current is
generated.
DC Output
S
H
A
F
T
Magnet
Magnet
Coils
Magnetic Recording
Write data by magnetizing
recording media (e.g., video
tape, hard disk) using
electromagnets.
Data is read back using the
induced current produced
when magnetized media
moves past receiver coils
(reverse of writing data).
Hard disk
EMP (ElectroMagnetic Pulse)
A strong, rapidly fluctuating magnetic pulse can
induce high voltage, causing strong currents.
In 1962, a nuclear test
in the Pacific produced
an EMP that knocked
out 300 streetlights
and telephone service
in the Hawaiian islands,
900 miles from the
explosion.
Starfish Prime, as seen from Honolulu
Call of Duty:
Modern Warfare 2 (2009)
In the “Second Sun” campaign mission a
nuclear missile creates a high-altitude EMP.
Streetlights explode, helicopters fall out of the sky,
and electronic equipment on weapons is “fried.”
Next Lecture
Lighting & Optics
Part I
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