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1. How are frequency and wavelength related? They are INVERSELY related. As one goes UP, the other goes DOWN!. Catalyst. 2. What are the 3 primary colors of light? When combined, what do they create? RED, BLUE, GREEN. Create WHITE light!. 3. Draw a convex and concave lens. Magnets!.
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1. How are frequency and wavelength related? They are INVERSELY related. As one goes UP, the other goes DOWN! Catalyst 2. What are the 3 primary colors of light? When combined, what do they create? RED, BLUE, GREEN. Create WHITE light! 3. Draw a convex and concave lens.
A little intro… • http://video.nationalgeographic.com/video/kids/cartoons-tv-movies-kids/i-didnt-know-that-kids/idkt-magnets-kids/
Properties of Magnets • A magnet is any material that exerts a magnetic force. • Magnets attract or repel other magnets. • One part of a magnet will always point north when allowed to swing freely
Magnetic Fields • The magnetic field is the area of magnetic force around a magnet • Allows magnets to interact without touching • Magnetic field lines are the invisible lines that map out the magnetic field of a magnet • Form complete loops, never cross • Always leave north and enter south • Distance between field lines indicate the strength of the magnet • Closer the lines, stronger the lines
Magnetic Domains • A magnetic domain is a region where the magnetic fields of all atoms are lined up in one direction • If the material is NOT magnetized, the magnetic domain points in random directions • If the material is considered a magnet, the magnetic domains are arranged in the same direction
Magnetic Materials • A ferromagnetic material is a material that shows strong magnetic properties • Behaves like a piece of iron • Iron, nickel, cobalt, samarium • Alloy magnets - magnets made from several different metals • Alnico - aluminum, nickel, iron, cobalt • Platinum and cobalt • Ferrite - mixture of substances that contain ferromagnetic elements • Most commonly used today • Brittle material but inexpensive
Making Magnets • Unmagnetized material can be magnetized by: • Placing an unmagnetized ferromagnetic material in a strong magnetic field • Rubbing the material with one pole of a magnet • Magnetizing a paper clip • Rub the paperclip in one direction along one pole of the magnet • Magnetic field of the magnet causes some domains in the paperclip to line up.
Destroying Magnets • Temporary magnet is a magnet made from a material that easily loses its magnetism • Permanent magnet is a magnet made from a material that keeps its magnetism for a long time • No magnet can last forever • Ways to demagnetize magnets • Drop it • Strike it • Heat it
Breaking Magnets • Break a magnet in half and you will have two smaller magnets • Each smaller magnet has its own north pole and south pole • Magnetic poles are lined up in one direction, which will remain even if the magnet is broken S N
Static Electricity • The buildup of charges on an object is called static electricity • Static discharge is the movement of charges from one object to another. • Think of this like shocking yourself when you drag your feet on the carpet and touch a door handle. • You feel the “shock.” • What you really experienced is static discharge. • Lightning is also a discharge of static electricity!
A Message from…Bill Nye • http://www.youtube.com/watch?v=Z-77IzaXGcg
How are charges transferred? 3 ways: • Friction – rub 2 objects together • Conduction – direct contact (touching) • Induction – without touching • Van der Graaff is a GREAT example!
A message from our sponsor • http://www.youtube.com/watch?v=gixkpsrxk4Y
Electric Current • Electric current is the continuous flow of electric charges (electrons) through a material. • Measured in amps (A) • Amps = amount of charge flowing past a given point each second. • AC = Alternating Current (runs in BOTH directions) • DC = Direct Current (runs in ONE direction)
Conductors and Insulators • A conductor is a material through which charges can flow easily. • An insulator is a material through which charges cannot flow easily.
Circuits • In order for electric current to exist, a circuit must first exist. • An electric circuit is a complete, unbroken path through which electric charges can flow.
Voltage • Potential energy is capacity to do work. • Batteries provide electrical potential energy • Voltage is the difference in electrical potential energy between two places. • This can also be called potential difference • Voltage causes current in an electric circuit • Basically, it is the amount of force pushing an electric current • Measured in Volts (V)
Resistance • Resistance is the measure of how difficult it is for charges to flow through a material. • Increase the resistance, decrease the current • Measured in ohms • Best Wire = SHORT, FAT, COLD! • Insulators = HIGH resistance • Conductors = LOW resistance
The Maglev TrainCan a magnet be used to make a train reach speeds of 2,000 mph?
Electric Current & Magnetism • Wherever there is electricity, there is magnetism • An electric current produces a magnetic field • This relationship is called electromagnetism
Parts of an Electromagnet Wire to wrap around the core, preferably made of copper. We call this wire a SOLENOID! Ferromagnetic material for a core, like a nail Energy Source like a battery Common Examples: credit cards, doorbells, radios, cranes, refrigerators, computer hard drives, VHS tapes, microwaves, etc.
Benefits of Electromagnets • It can be turned on and off • It can have its direction reversed • We have control over the strength
How can we manipulate Electromagnets? • Change the number of coils of the solenoid. • More coils = stronger • Less coils = weaker • Change the ferromagnetic core • More iron = stronger • Less iron = weaker • Change the source • Higher voltage = stronger • Lower voltage = weaker
Apply it?? • Kinda Creepy?? http://videos.howstuffworks.com/discovery/40183-mythbusters-electromagnetic-turkey-video.htm • James Bond? http://videos.howstuffworks.com/discovery/32911-mythbusters-clips-electromagnetic-watch-video.htm • Boom?? http://science.howstuffworks.com/7102-electromagnetic-pulse-bomb-video.htm
Introduction and Overview • http://www.youtube.com/watch?v=x2EuYqj_0Uk
Series Circuit • Only ONE path. • Resistance is constant. • If one bulb goes out, the entire strand goes out. • The more lights you add, the dimmer the strand becomes. • The resistance is shared equally.
Series Circuit • Benefit: safety switch • Drawback: a DC flow (direct current in ONE direction) • Examples: security systems, OLD Christmas lights
Parallel Circuit • Multiple paths for current to flow. • Resistance varies. • Light may shine brighter based on resistance. • Bulbs will stay lit even when a light burns out or breaks.
Parallel Circuit • Benefits: very controllable; more dependable • Drawbacks: voltage and resistance vary, harder to turn off due to being an AC flow (alternating current) • Examples: wiring in your home, NEW Christmas lights
Side by Side Series Parallel
Series and Parallel Circuits Game • http://scienceofeverydaylife.discoveryeducation.com/views/other.cfm?guidAssetId=D1507F6E-09C3-4E7B-B1E9-16708E402009