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NOTE: This presentation was not made for public use. Please do not use this presentation without my permission and the permission of each of the authors of the photographs, quotes, and other materials that they contain. Thank you, Vicki Hughes Labs and Activities for this Presentation: Balloon Hair Christmas Lights and Batteries
Electric charge is a physical property of particles causing them to attract or repel each other WITHOUT TOUCHING! Step 1: Scuff your feet as you walk across carpet. Step 2: Touch a metal doorknob. Step 3: Say OUCH! because you just got a shock! You were shocked by the doorknob because of moving electric charges.
Atoms are neutral when they have the same number of electrons and protons. + -
Atoms become positively charged when they have fewer electrons than protons. They are then called CATIONS. + - CATION
Atoms become negatively charged when they have more electrons than protons. They are then called ANIONS. + - - ANION
All electric charge is based on the protons (+ charge) and electrons (- charge) in atoms. Like charges repel. ++-- -+ Opposites attract! Electric Force is the attraction or repulsion between charged particles.
An ELECTRIC FIELD is a space around a charged particle where the particle exerts a force. +-
The buildup of charges is known as static electricity.
A balloon rubbed against your hair will cause it to transfer electrons from your hair to the stronger balloon. The hair is attracted to the balloon. The hair becomes + and the balloon becomes -. Friction and Electric Charge Balloon Hair
Static discharge occurs when built up static charge is suddenly released.
Electric Current Electric Current is a continuous flow of electric charges. Water can flow. People can flow. Electrons can flow. Energy Stick Demo
Current is measured as the amount of charge that flows past a given point in a certain amount of time. Electric current can flow in one direction…Direct Current: or it can keep changing directions…Alternating Current: Potential Difference (Voltage) = difference between starting point and ending point of a current. high low
Resistance is the opposition to the flow of electric currents. George Ohm Resistance is caused by electrons bumping into particles in matter. e- Resistance is futile? Nah, but it slows you down! e- Georg Ohm
Conductors have LOW resistance and allow current to flow. George Ohm Let the current flow!
Insulators have HIGH resistance and DO NOT allow current to flow. George Ohm Stop that current flow! Conductors and Insulators Electric Fence 0:53 http://www.youtube.com/watch?v=4SIT0aU_FRw http://www.youtube.com/watch?v=4SIT0aU_FRw
Insulated wire is made of conductive metal wire surrounded by a nonconductive plastic or rubber coating. George Ohm
Semiconductor = partially conducts circuits can be carved into the surface circuits are good conductors very energy-efficient
Superconductor = very high conductivity when cold more efficient than regular conductors
Any Questions? NYC Blackout 10:14 http://www.youtube.com/watch?v=6nt0njgVmv4
Aurora Borealis is a result of the response of Earth’s magnetic field to solar flares. MAGNETISM
Properties of MAGNETS Magnet = object that attracts certain materials such as iron. Quick Lab: Wooly Willy
Properties of MAGNETS Magnetic Poles A magnetic pole is a region where the magnet is strongest. All magnets have two magnetic poles. The poles are called “north” and “south” because they line up with the Earth’s axis.
Properties of MAGNETS Magnetic Poles If you cut a magnet apart in the middle, it will establish two new poles. Pieces of magnets will always have a north and south pole. N S NN S Poles are on faces. N S
MAGNETIC FORCE NSNS REPELS!ATTRACTS! Magnetic Force is the force exerted over a distance. Repulsion = pushing Attraction = pulling Activity: Discovering Magnets
A Magnetic field is a space around a magnet that exerts a force. NSNS MAGNETIC FIELD
When two OPPOSITE magnetic fields interact, they bend toward each other and pull. NSNS
When two of the same magnetic fields interact, they bend away from each other and push. SNNS
MAGNETISM Magnetism is due to the movement of electrons. http://www.wimp.com/magnetswork/
ELECTRICITY AND MAGNETISM Electromagnetism is magnetism produced by an electric current. Denmark 1820 Hello! I am Dr. Oersted. Please join me. Let me tell you how I discovered the relationship between electric currents and magnetic fields.
ELECTRICITY AND MAGNETISM Denmark 1820 It all happened like this… I was trying to show my students that electricity and magnetism are not related. I placed a wire with electric current flowing through it next to a magnet, and nothing happened. NS
ELECTRICITY AND MAGNETISM Denmark 1820 After class, a student held the wire near the magnet again, but in a different direction. To my surprise, the pointer of the magnet swung toward the wire so it was no longer pointing to Earth’s magnetic north pole. N S With more experiments, I was able to show the lines of magnetic fields.
ELECTRICITY AND MAGNETISM Denmark 1820 I’m so proud of my little pooky-bear! Aw, mom! Thank you for visiting. Good night everyone. Click!
ELECTRICITY AND MAGNETISM The magnetic field created by an electric current flowing through a wire actually surrounds the wire in circles. This magnetic field is stronger as more current flows through the wire. The direction of the magnetic field depends on the direction the current is flowing.
Solenoid = a coil of wire with electric current flowing through it, giving it a magnetic field. ELECTROMAGNETISM
The magnetic field around a coiled wire has north and south poles like a bar magnet. ELECTROMAGNETISM
The magnetic field around a coiled wire is stronger because each turn of the wire has its own field. ELECTROMAGNETISM Therefore, more coils mean stronger magnetism. 31 coils 16 coils
Solenoids are the basis for electromagnets. ELECTROMAGNETISM Electromagnet = solenoid wrapped around a bar of iron. How to make an electromagnet 4:58 http://www.youtube.com/watch?v=emlzh9XXWgQ
ELECTROMAGNETISM Electromagnetic induction = generating electricity in a wire by moving a magnet nearby. How to make an electromagnet 4:58 http://www.youtube.com/watch?v=emlzh9XXWgQ
Project Assignment: (Works = 100; Doesn’t work = 90) Projects count as test grades! ELECTROMAGNETISM Make your own electromagnet using a nail, some wire, and a battery. We will test your battery in class. http://www.youtube.com/watch?v=nMmldOU6t8I
Using electromagnets ELECTROMAGNETISM http://www.youtube.com/watch?v=JWh2qT9yiTo
ELECTRICITY Electric transformers use electromagnetic induction (moving magnetic fields past electric fields) to change the voltage of electric current.
ELECTRICITY Coils for incoming current create a magnet on the P side. That magnet then creates a magnet on the S side. The S side magnet creates an S side current.
ELECTRICITY The number of coils on each side determines if the current is increased or decreased as it flows through the transformer.
Any Questions? Power of Electricity (Transformer Explosions) 10:09 http://www.youtube.com/watch?v=yX5TIDLvMyw http://www.youtube.com/watch?v=yX5TIDLvMyw ACT L17