Transcript Science Olympics

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Understanding Electricity…
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Hair Raising Experience
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You walk across the rug, reach for the doorknob and..........ZAP!!!
You get a shock.
Or, you come inside from the cold, pull off your hat
and......BOING!!! All your hair stands on end. What is going on
here? And why does it only seem to happen in the winter?
The answer is:
Katarin MacLeod
STATIC ELECTRICITY
http://www.sciencemadesimple.com/static.html
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Law of Conservation of Charges
Neutral Objects and Charged Objects attract
and…
Katarin MacLeod
KATARIN MACLEOD
http://www.sciencemadesimple.com/static.html
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Balancing of Charges
http://www.sciencemadesimple.com/static.html
Katarin MacLeod
KATARIN MACLEOD
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So how does this work?
http://www.photographersdirect.com/buyers/stockphoto.asp?imageid=65334
Katarin MacLeod
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• Van der Graff (VDG) generator is a machine that
continually draws electrons off a large metal
dome. The dome thus becomes strongly
positively charged once the machine is turned
on.
http://www.ap.stmarys.ca/demos/content/e_and_m/hair_raising/hair_raising.html
Katarin MacLeod
KATARIN MACLEOD
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Tesla and his Invention
Katarin MacLeod
http://www.tb3.com/tesla/
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http://bhs.broo.k12.wv.us/homepage/alumni/dstevick/tc.htm
Katarin MacLeod
KATARIN MACLEOD
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The Fine Details…
• The Tesla coil is a dynamic device. High voltage radiofrequency current is produced at the rate the spark-gap fires.
• 120 times a second would be typical.
• Maximum arcs are produced in profusion immediately and
continue for as long as the coil is left running.
• The sparks, poorly visible in strong light, appear quite strong
in subdued lighting conditions.
• The arcs are purplish to whitish depending on whether they
are allowed to go to the open air or are drawn to a nearby
grounded rod or wire.
• A ground wire held close produces very intense sparks.
Katarin MacLeod
http://bhs.broo.k12.wv.us/homepage/alumni/dstevick/tc.htm
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Safety of Tesla Coils…
• Tesla coils are not harmless toys. One must constantly
be watchful of what is touched.
• It is said that the r.f. current from the coil flows over the
surface of the skin, and is therefore not capable of killing.
• However, it is also known that contacting a high-powered
discharge can cause burns and is extremely painful. The
primary circuit of the coil is where the true danger lies;
plenty of voltage and amperage here.
• An inadvertant touch of a fully charged primary capacitor,
even with the coil *off*, can kill you.
• Primary voltages run up to 15,000 volts, but the
discharger puts out anywhere from a quarter-million to a
couple million volts depending on the input power.
Katarin MacLeod
KATARIN MACLEOD
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Static Electricity & Balloons
Question:
How can you make a balloon stick to the
wall when only given the balloon?
Katarin MacLeod
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Answer
If you charge a balloon by rubbing it on your hair, it picks
up extra electrons and has a negative charge.
Holding it near a neutral object will make the charges in
that object move. If it is a conductor, many electrons
move easily to the other side, as far from the balloon
as possible.
If it is an insulator, the electrons in the atoms and
molecules can only move very slightly to one side,
away from the balloon.
In either case, there are more positive charges closer to
the negative balloon. Opposites attract. The balloon
sticks.
Katarin MacLeod
http://www.sciencemadesimple.com/static.html
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Step 2: Using dryer sheets
What affect will occur if a
charged balloon is then
rubbed with a dryer sheet?
Will it still stick to the wall?
Katarin MacLeod
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The balloon will not stick to the wall because
the dryer sheet removes the extra
electrons added to the balloon…
Therefore, the balloon is now NEUTRAL
and will not stick to the wall.
What charge must be on the dryer sheets?
Katarin MacLeod
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Direct Current Electric Circuits
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/dccircon.html#c1
Katarin MacLeod
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Series Circuits
In a series circuit, all
elements are
attached to make one
complete path.
Here a battery is
attached to three
lights.
http://www.msnucleus.org/membership/html/k-6/as/technology/4/ast4_3a.html
Katarin MacLeod
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Real life Circuits vs. Schematic Drawings
This drawing is a series circuit with a battery ( 3 cells
connected in series) and three lights (loads or
resistors).
http://www.glenbrook.k12.il.us/gbssci/phys/Class/circuits/u9l4a.html
Katarin MacLeod
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DC Parallel Circuits
The following is a parallel circuit. Notice the wires
are arranged such that the lights will be in parallel
with each other.
Katarin MacLeod
KATARIN MACLEOD
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Real life Parallel Circuit vs.
Schematic Diagram
http://www.glenbrook.k12.il.us/gbssci/phys/Class/circuits/u9l4a.html
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Science Fairs & Science Olympics
• There are stages to Science Fairs:
School
Regional
Provincial
National
International
• All grades can participate and projects are
grouped depending on grade and topic
• Money and scholarships are given out as
students progress through the various stages of
fairs
http://www.physics.uwo.ca/sfair/sflinks.htm
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More on Science Fairs…
For examples:
http://school.discovery.com/sciencefaircentra
l/ (separate science fair guides for
students, teachers and parents)
http://www.scifair.org/ (“ultimate science fair
resource – science project help & ideas)
http://www.virtualsciencefair.com/ (Canada
wide virtual science fair for K-12)
Katarin MacLeod
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Science Olympics
• The general idea is that students pursue
excellence through science and/or competition.
• These can be held at a school or regional level.
• Best site:
http://www.physics.uwo.ca/olympics
Katarin MacLeod
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Welcome to the
First Annual
Secondary Science Olympics
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First Event…
The Solo-Electromagnet
Competition
• In pairs, work to build an electromagnet.
• Materials: 1m of wire, 1 nail, 1 9V battery,
and paperclips
Katarin MacLeod
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Procedure
• Wrap the wire around the nail
• Attach the ends of the wire to the terminals of
the battery
• Try to pick up as many paperclips with the
electromagnet as possible
• The maximum number of paperclips is your
score for this event.
Katarin MacLeod
KATARIN MACLEOD
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Second Event…
The Duo-Boat Float
• In pairs, you will build a boat from Aluminum foil
and test for buoyancy
• Materials: 1 15cm x 15cm piece of Aluminum
foil, container of water, & washers.
Katarin MacLeod
KATARIN MACLEOD
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Procedure
• Create a boat from the Aluminum foil
• Test to see if it floats
• Add pennies, washers or nails to your boat until
it sinks into the water
• The number of items added to your boat is your
score for this event.
Katarin MacLeod
KATARIN MACLEOD
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The Third and Final Event…
The Quad-Straw Free Standing
Tower
• In groups of 2, you will build the tallest possible
free standing tower.
• Materials: 10 straws, 1 sheet of paper, 20cm of
tape
Katarin MacLeod
KATARIN MACLEOD
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Procedure
• From the materials given, construct the
tallest possible tower
• When all towers are complete, the tallest
in the class will receive 100 points, the
second tallest will receive 50 points and
the third tallest will receive 25 points.
Katarin MacLeod
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Calculating Time…
Solo-Electromagnet: # of paperclips
Duo-Boat Float: # of pennies held
Quad Straw Free Standing Tower: points
Final Score: ____________
Congratulations!
Katarin MacLeod
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Thank you for
Participating
Have a Great Day
Prizes will be awarded
On Wednesday!

Katarin MacLeod
KATARIN MACLEOD