Catalyst 1. How are frequency and wavelength related? They are INVERSELY related. As one goes UP, the other goes DOWN! 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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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

Mythbusters: Magnets Mythbusters: Magnets Can magnets be used to climb a wall?

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 SN

Electricity

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!

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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!

Electric Currents

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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

Electromagnetism

The Maglev Train The Maglev Train Can 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 Energy Source like a battery Ferromagnetic material for a core, like a nail Wire to wrap around the core, preferably made of copper. We call this wire a SOLENOID ! 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

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Series and Parallel Circuits

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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

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