ELECTRICITY - REVIEW QUIZ

ELECTRICITY - LIGHTNING RODS

Lightning Rods

Lightning rods were originally developed by Benjamin Franklin.
A lightning rod is very simple -- it's a pointed metal rod attached to the roof of a building.

• The rod might be an inch (2 cm) in diameter. It connects to a huge piece of copper or aluminum wire that's also an inch or so in diameter. The wire is connected to a conductive grid buried in the ground nearby.

The purpose of lightning rods is often misunderstood. Many people believe that lightning rods "attract" lightning. It is better stated to say that lightning rods provide a low-resistance path to ground that can be used to conduct the enormous electrical currents when lightning strikes occur. If lightning strikes, the system attempts to carry the harmful electrical current away from the structure and safely to ground. The system has the ability to handle the enormous electrical current associated with the strike. If the strike contacts a material that is not a good conductor, the material will suffer massive heat damage. The lightning-rod system is an excellent conductor and thus allows the current to flow to ground without causing any heat damage.

Lightning can "jump around" when it strikes. This "jumping" is associated with the electrical potential of the strike target with respect to the earth's potential. The lightning can strike and then "seek" a path of least resistance by jumping around to nearby objects that provide a better path to ground. If the strike occurs near the lightning-rod system, the system will have a very low-resistance path and can then receive a "jump," diverting the strike current to ground before it can do any more damage.

As you can see, the purpose of the lightning rod is not to attract lightning -- it merely provides a safe option for the lightning strike to choose. This may sound a little picky, but it's not if you consider that the lightning rods only become relevant when a strike occurs or immediately after a strike occurs. Regardless of whether or not a lightning-rod system is present, the strike will still occur.

If the structure that you are attempting to protect is out in an open, flat area, you often create a lightning protection system that uses a very tall lightning rod. This rod should be taller than the structure. If the area finds itself in a strong electric field, the tall rod can begin sending up positive streamers in an attempt to dissipate the electric field. While it is not a given that the rod will always conduct the lightning discharged in the immediate area, it does have a better possibility than the structure. Again, the goal is to provide a low-resistance path to ground in an area that has the possibility to receive a strike. This possibility arises from the strength of the electric field generated by the storm clouds.

ELECTRICITY - ASSIGNMENTS

  ELECTRICITY ASSIGNMENTS  

All assignments due on Electricity Unit Quiz - March 26, Wednesday

•  Electricity Cloze Modules 1-11

• Electricity Cloze Modules A-E

    

MAKE SURE TO READ, TAKE NOTES, & STUDY EACH EVENING OVER ALL THE MATERIAL.

 DO ALL ACTIVITIES , WATCH VIDEO CLIPS,     

POWER POINTS & QUIZZES

 2/24

ELECTRIC QUIZ #1

ELECTRICITY SCAVENGER HUNT #1

ELECTRICITY SCAVENGER HUNT #2

ELECTRICITY SCAVENGER HUNT #3

2/18

POWER POINTS

QUIZ REVIEW – ELECTRICITY #1

 2/6

MODULE  #4 – POWERPOINT

2/19

MAGNETS & ELECTRIC CURRENTS - QUIZ

ENERGY TRANSFORMER & STORAGE - QUIZ

ELECTRICITY - CHEAT SHEET

ELECTRICAL EQUATIONS

Voltage = Volts                        Current = Amps                       Resistance = Ohms

Voltage = Current  x Resistance

Current = Voltage / Resistance

Resistance = Voltage / Current

Watts = Joules/second

Volts * Amps = Watts

Electric Power = rate @ which energy is transformed from one form to another

Power = Watts

1 Kilowatt is 1,000 watts

• 1 watt is equal to 0.001 kilowatt.

Watts * Time = Joules or total energy consumed

Increasing Voltage increase the current

Increasing the Resistance will decrease the current

Voltage & current are directly proportional

Current & Resistance are inversely proportional

HOW STATIC ELECTRICITY IS PRODUCED

1. When two different objects that are insulators (such as a plastic rod and silk cloth) are rubbed together, electrons move from one object to another.

2. One object becomes negatively-charged, and the other object becomes positively-charged.

3. The more rubbing, the more electrons are transferred, and the larger is the charge built up.

4. Unlike charges (positive and negative) attract each other.

·   Current Electricity or electric current is the movement of negatively-charged electrons through wires or objects with metals, carbon or water.

·   Conductors are substances that allow electrons to travel easily through them (e.g. metals, carbon and water).

·   Insulators or non-conductors are substances that do not allow electrons to travel easily through them (e.g. plastic and wood).

·   Resistors are substances that are poor conductors. They convert much of the energy of moving electrons into light, heat or sound energy in light bulbs and stereos.

·             

A simple cell consists of 2 different conductors (electrodes) partly covered by an acidic or ionic solution (electrolyte solution).

·     Different combinations of electrodes produce different

·      voltages.                                

·   For example, electrodes of zinc 

    and copper produce 1.1 volts, whereas electrodes of 

    aluminum and carbon produce     

    2.4 volts.

·   Rechargeable Cells (e.g. lead-acid cells) are cells that can be recharged when they go 'flat' by reversing the chemical reaction.

·   Electrical power is the amount of electrical energy used    by an appliance every second. It is measured in Watts.

·   When paying for electricity, we use the unit kiloWatt-hour (kWh). One kWh is the energy used by a 1000 watt appliance switched on for one hour.

·   Example:

Q. A 200 watt TV set is used for 6 hours. How many kilowatt-hours of electricity were used?

A. Number of kWh	= kilowatts × number of rating hours
	= (200 W⁄1000) × 6 h
	= 1.2 kWh

SERIES CIRCUIT

• Series Circuit - a circuit where the components are connected one after the other into a 'circle'.
• Ammeter - This device is used to measure current in amperes (A). It must be wired into the circuit in series.
• Disadvantages of Series Circuits - As more light bulbs are connected in series, the brightness of all bulbs decreases.

PARALLEL CIRCUITS

• Parallel Circuits are combined circuits where components such as light bulbs glow equally brightly.
• This form of wiring is used in household circuits.
• Voltmeter - a device for measuring voltage (or
• potential difference), and must be wired into the
• circuit in parallel
• Short Circuit - A short circuit occurs when a
• conducting object such as a screwdriver lies
• between two circuits. The electrons take the
• 'shorter' circuit through the screwdriver.

HOUSEHOLD CIRCUITS

• Fuse - The fuse is a thin wire with a low melting point near the power source to a house. It heats up readily and melts to disconnect the circuit to the house when excessive current flows. The fuse may 'blow' in the event of a power surge to the house, or due to a faulty electrical appliance in the house. A circuit-breaker serves a similar purpose.
• Ground/Earth Wire - All households must have a connection between the household wiring and the earth. This is to carry away any extra surge of electricity that may occur during lightning storms or as a result of a faulty appliance.
• Electric Plug - Most electric plugs have 3 connections - Active or 'Live' (brown), Neutral (blue) and Earth (green/yellow). However, appliances with plastic exteriors do not always have the third earth connection.
• DC (Direct Current) - Direct current is a current in which electrons continually flow in the one direction. It is produced by batteries.
• AC (Alternating Current) - Alternating current is a current of electrons in which the direction of movement of electrons is continually changing. It is the type of current in household and industrial circuits.

3 WAYS OF GENERATING ELECTRICITY

1. Using Chemical Reactions in Electric Cells - The chemical energy of the electric cell is converted to electrical energy.
2. Using Light in Solar Cells - Solar or photo voltaic cells are made of elements such as silicon which readily free electrons when exposed to sunlight energy. The light energy is converted into electrical energy.
3. Using Magnets - Moving a magnet through a coil of wire causes the electrons to flow through the wire. This is called the electromagnetic effect or induction. Moving the magnet in the opposite direction causes the current to reverse. To increase the current, one can increase the strength of the magnet, the number of turns in the coil, or the speed of movement of the magnet.

OHM'S LAW 

• Voltage or Potential Difference (volts, V) = Current (amperes, A) × Resistance (ohms, Ω)

I =	V
	R

V = I × R

R =	V
	I

ELECTRICITY SYMBOLS

The best real-life example of direct current is a battery.

Batteries have positive (+) and negative (-) terminals. If you take a wire and connect the positive and negative terminals on a battery, the electrons in the wires will begin to flow to produce a current. You can prove that the current is flowing if you connect a small light to the circuit. The light will begin to glow as the electrons pass through the filaments.   Everything that uses batteries runs on DC power.

Electric wiring in your house is AC power and it is completely different than DC.

The electricity produced by a generator travels along cables to a transformer, which changes electricity from low voltage to high voltage. Electricity can be moved long distances more efficiently using high voltage. Transmission lines are used to carry the electricity to a substation. Substations have transformers that change the high voltage electricity into lower voltage electricity. From the substation, distribution lines carry the electricity to homes, offices and factories, which require low voltage electricity.

Household electricity is around 240 volts in 

 some countries and 110v. in others. Such 
high voltages may give you deadly shocks,
so appliances are protected by "fuses".
Fuses, contain thin pieces of wire that melt
and cut off current if it is too large. Electricity
is carried to the different parts of the house
by parallel circuits. The parallel circuits
contain 2 wires called the "live and neutral
wires". Some countries use "Earth wire",
which is a safety device that provides a path
to the ground which electric current can
escape

Electrical Power

• Electrical power is the amount of electrical energy used by an appliance every second. It is measured in Watts.
• When paying for electricity, we use the unit kiloWatt-hour (kWh). One kWh is the energy used by a 1000 watt appliance switched on for one hour.
• Example:

Q. A 200 watt TV set is used for 6 hours. How many kilowatt-hours of electricity were used?

A. Number of kWh	= kilowatts × number of rating hours
	= (200 W⁄1000) × 6 h
	= 1.2 kWh

ELECTRICITY ACTIVITIES

WHAT IS ELECTRICITY - ACTIVITY#1

ELECTRICITY CIRCUIT - ACTIVITY #2

ELECTRIC CIRCUIT - ACTIVITY  #3

HOW A BATTERY WORKS - ACTIVITY #4

BENJAMIN FRANKLIN - ELECTRICITY ACTIVIY #5

ELECTRICITY - ACTIVITY #6

ELECTRICITY - QUIZ #1

ELECTRICITY SCAVENTER HUNT #1

ELECTRICITY SCAVENGER HUNT #2

ELECTRICITY SCAVENGER HUNT #3

• Complete the hunts' answers in your notebook

ELECTRICITY - POWERPOINTS FOR REVIEW & QUIZ

Jeff Taylor

ELECTRICITY REVIEW ACTIVITY - #1


QUIZ REVIEW - ELECTRICTY #1

• WRITE YOUR NAME 
• QUIZ NAME 
• SCORE 
• ON NOTEBOOK PAPER & TURN IN TO DRAWER

ELECTRICITY - QUEST

ELECTRICITY 
Read pages - 32 through 38
Take notes
Answer any questions

• write questions & answers

HISTORY OF ELECTRICITY 
Read page - 63
Take notes
Answer any questions

• write questions & answers

ELECTRICITY HAND-OUTS 
Read & complete p. 26 -30
DUE:  2/21, Friday

ELECTRICITY - STATIC ELECTRICITY - #11

Static Electricity

Static electricity is the build up of an electrical charge on the surface of an object. It's called "static" because the charges remain in one area for a while rather than moving or "flowing" to another area. 
We see static electricity every day. It can even build up on us. For example, when we rub our feet on the carpet and then zap something when we touch it. That is static electricity that we have built up on the surface of our skin discharging onto another object. We also see it when our hair gets charged and sticks straight up or when our pant legs keep sticking to our legs no matter what we try and do. This is all static electricity that has built up on the surface of an object. 

Lightning is a powerful form of static electricity

What is static electricity? 
In the study of atoms we learned that atoms are made up of neutrons, protons, and electrons. The electrons are spinning around the outside. A static charge is formed when two surfaces touch each other and the electrons move from one object to another. One object will have a positive charge and the other a negative charge. Rubbing the items quickly, like when you rub a balloon fast over something or your feet on the carpet, will build up a large charge. Items with different charges (positive and negative) will attract, while items with similar charges (positive and positive) will push away from each other. Sort of like a magnet. 

Remember when you've gone down a slide and all your hair stands up straight. This is because the friction of sliding has caused a positive charge to be built up on each hair. Since each hair has the same charge, they all try to push away from each other and end up standing up straight. 
Likewise, when your skin is charged with static electricity and you touch something metal, like a door handle, the metal is very conductive and will quickly discharge the static electricity, creating a zap or small spark. 
Does it have any real uses? 
Static electricity has several uses, also called applications, in the real world. One main use is in printers and photocopiers where static electric charges attract the ink, or toner, to the paper. Other uses include paint sprayers, air filters, and dust removal. 

It can damage electronics 
Static electricity can also cause damage. Some electronic chips, like the kind that are in computers, are very sensitive to static electricity. There are special bags to store these in. Also, people that work with these kind of electronics wear special straps that keep them "grounded" so they won't build up charge and ruin the electronic components. 
Fun facts about static electricity
A spark of static electricity can measure thousands of volts, but has very little current and lasts for a short period of time. This means it has little power or energy.

• Lighting is a powerful and dangerous example of static electricity.
• As dangerous as lighting is, around 70% of people struck by lightning survive.
• Temperatures in a lightning bolt can hit 50,000 degrees F.
• Static electricity will be worse on a dry non-humid day.