# I. is a force defined as the movement of negatively charged electrons.

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I. is a force defined as the movement of negatively charged electrons.

A. Types of Electricity  1. Static is not moving.  An example of this would be a person rubbing his feet against carpet and touching a conductor.  What is a conductor?  A conductor is something that allows electricity to flow.

a. Lightning  Why do we see lightning before we hear thunder?  Since light and sound travel at different speeds, we see the lightning before we hear the thunder. They occur at the same time, however.

2. Current Electricity  Also known as moving or electric energy.  Electricity needs a force to push the electrons into a flow (batteries or generators).

II. Conductors vs. Insulators  Conductors allow electricity to move through them.  Insulators do not allow electricity to move through them.  Give an example of a conductor.  Copper, water, and aluminum are good conductors.  Give an example of an insulator. Plastic, wood, and glass are insulators,

Which is best to hold if I am heating a liquid in a metal pan?

A. Current  Current is the amount of electrons passing through an area at one time.  It is measured in Amps.  Current may be direct (DC) or alternating (AC).  Alternating current moves in one direction and then moves in the opposite direction, switching back and forth in direction.

Direct Current  If an alternating current switches directions, how does direct current move?

Why have two types of current?  It allows us to transport energy more efficiently over a greater distance.

B. Resistance  This is the force NOT allowing electrons to move easily.  It is measured in Ohms.  Question: Something with a low resistance is a good conductor. True or false?  Give an example of a conductor.

1. Insulators  An insulator does NOT allow electrons to move through it easily.  We use copper as a conductor in our electrical plugs.

Insulators  Electrical plugs are coated with an insulator.  What is the insulator?  Why is it needed? Electrical plugs are coated with an insulator. What is the insulator? Why is it needed?

III. How do we get electrons moving?  Forces that start the flow of energy:  Batteries can do this.  They store chemical energy.  One end of the battery contains extra electrons (so it will have what type of charge?)  The opposite end of the battery has too few electrons (so it will have what type of charge?)

A. Units of Energy  Amps = Current is the amount of electrons passing through an area at one time.  Ohms = Resistance or the force not allowing electrons to move.  Watt = energy used per second  Voltage = Current (I) x Resistance (R)

Resistance  Human body has a resistance of 500,000 Ohms if dry.  Human body has a resistance of 100 Ohms if wet.  Salt lowers resistance even more.  Why is it not a good idea to be in a tub during a thunder storm?

Why is this not a good place to be during a lightning storm?  The chance of electrocution is increased drastically.  The tub may also be connected to a metal pipe that runs to the ground.

B. Circuits are the paths for electrons: 2 types  Series – all energy flows through the same path (like x-mas lights, if one goes out they all go out)  Parallel – energy flows to each bulb (like in your homes)

When you flip a light switch, you complete the circuit.  The electrons (chemical energy) are sent through a light bulb (which has a high resistance) and heat energy is produced.  Heat energy changes to light energy.

What’s in your bulb?  At the bulb base, bulbs have two metal contacts, which connect to the ends of an electrical circuit.  The metal contacts are attached to two stiff wires, which are attached to a thin metal filament. The filament sits in the middle of the bulb, held up by a glass mount.  The wires and the filament are housed in a glass bulb, which is filled with an inert gas, such as argon.

Moving current…  When the bulb is hooked up to a power supply, an electric current flows from one contact to the other, through the wires and the filament.

How do electrons move???  As the electrons zip along through the filament, they are constantly bumping into the atoms that make up the filament. The energy of each impact vibrates an atom -- in other words, the current heats the atoms up.  It’s almost like a domino effect. One atom moves, so another moves, and another, and so on.

What are photons?  Bound electrons in the vibrating atoms may be boosted temporarily to a higher energy level. When they fall back to their normal levels, the electrons release the extra energy in the form of photons.  Metal atoms release mostly infrared light photons, which are invisible to our eyes.  But, if they are heated to a high enough level -- around 4,000 degrees Fahrenheit (2,200 degrees C) in the case of a light bulb -- they will emit a good deal of visible light.

How much metal is in my bulb???  The filament in a light bulb is made of a long, incredibly thin length of tungsten metal. In a typical 60-watt bulb, the tungsten filament is about 6.5 feet (2 meters) long but only one-hundredth of an inch thick.  The tungsten is arranged in a double coil in order to fit it all in a small space. That is, the filament is wound up to make one coil, and then this coil is wound to make a larger coil.  Tungsten is used in nearly all incandescent light bulbs because it is an ideal filament material.

Light Photons

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