1. 1/18/10 Make a Claim: Last week we saw several examples of energy transformations in our labs, describe two of them. Objective: Students will be able to define & describe energy & electricity. Students will be able to define & describe energy & electricity. Students will summarize laws of thermodynamics. Students will summarize laws of thermodynamics. Agenda:HW: Claim/ share outComplete 6 ?s Electricity noteson back of Wrap up/ exit slipelectricity notes

2. What did our energy transformation labs teach us… The Laws of Thermodynamics!!!!

3. 1 st Law of Thermodynamics: Energy can be changed from one form to another, but it cannot be created or destroyed. The total amount of energy and matter in the Universe remains constant, merely changing from one form to another AKA The Law of Conservation of Energy

4. For Example The chemical energy inside of the wick and wax was not destroyed when the candle was burned. Instead it was transferred into light and heat energy and some of it remained.

5. How does this 1 st law fit with what we learned about in a food web? 1000 units of energy From sun 100 units from producer 10 units from 2 nd trophic level 1 unit from 3 rd Trophic level

6. 2 nd Law of Thermodynamics: Heat will always flow from areas of higher temperature to areas of lower temperature +=

7. For example A car that has run out of gas will not run again until you walk 10 miles to a gas station and refuel the car. Or another example: Once the potential energy locked in carbohydrates is converted into kinetic energy (energy in use or motion), the organism will get no more until energy is input again

8. “ energy ” Let’s explore this word further! Let’s explore this word further! It’s true that electricity gives energy to appliances, lights, and machines. It’s true that electricity gives energy to appliances, lights, and machines. But what is “energy”? But what is “energy”? Energy is the ability to do work Energy is the ability to do work What is energy capable of doing? What is energy capable of doing? Electricity is just one form of energy Electricity is just one form of energy

9. There are two main types of energy: Kinetic and Potential Kinetic energy is energy by motion (in waves, atoms, molecules, etc) Kinetic energy is energy by motion (in waves, atoms, molecules, etc) Potential energy is stored energy (the molecules of food or a large rock sitting at the top of a hill) Potential energy is stored energy (the molecules of food or a large rock sitting at the top of a hill)

10. Is the picture below illustrating kinetic or potential energy? How do you know?

11. Which type of energy is electricity? Kinetic! Kinetic! Electricity has a “current” or “waves of power” Electricity has a “current” or “waves of power” What is in this current and what makes it capable of making an object “do work”? What is in this current and what makes it capable of making an object “do work”?

12. Before we can explore current, we have to understand what is found in a current… Atoms! Atoms! Atoms are the smallest particle we can break matter down into Atoms are the smallest particle we can break matter down into We cannot see atoms We cannot see atoms All atoms are made up of 3 sub particles: All atoms are made up of 3 sub particles: - protons - neutrons -electrons

13. The charges of an atom In the center (nucleus) of an atom sits the protons and neutrons In the center (nucleus) of an atom sits the protons and neutrons Protons carry a + charge Protons carry a + charge Neutrons carry a neutral charge 0 Neutrons carry a neutral charge 0 On the outside of atoms electrons spin around the nucleus in orbitals On the outside of atoms electrons spin around the nucleus in orbitals Electrons carry a - charge Electrons carry a - charge

14. Staying Neutral Most atoms have an equal number of protons and electrons to maintain a neutral (0) charge Most atoms have an equal number of protons and electrons to maintain a neutral (0) charge For example 8 protons would have a charge of… For example 8 protons would have a charge of…+8 8 electrons would have a charge of… 8 electrons would have a charge of… - 8 The overall charge of the atom would be… The overall charge of the atom would be… 0

15. Of these three particles…which is the easiest to remove? Electrons are the easiest particle to remove from atoms Electrons are the easiest particle to remove from atoms If an electron is removed from our atom with 8 electrons and 8 protons, what happens to our charges? If an electron is removed from our atom with 8 electrons and 8 protons, what happens to our charges? We now have -7 and +8 We now have -7 and +8 The atom is no longer neutral The atom is no longer neutral It now has an overall charge of +1 It now has an overall charge of +1

16. How do charged objects behave? “opposites attract” “opposites attract” The object with a (-) charge has more electrons, it seeks the object with a (+) one to offload some of them The object with a (-) charge has more electrons, it seeks the object with a (+) one to offload some of them If it can give some of its (-) electrons to the (+) charged object it will become…. If it can give some of its (-) electrons to the (+) charged object it will become…. Neutral! Neutral! The goal for all objects: to stay neutral! The goal for all objects: to stay neutral!

17. This attraction of (-) to (+) causes electrons to move! An electric current is simply the movement (-) electrons from an area of high concentration to an area of low concentration. An electric current is simply the movement (-) electrons from an area of high concentration to an area of low concentration. YOU can make an electrical current! YOU can make an electrical current! Walking across a rug you rub electrons off of the rug Walking across a rug you rub electrons off of the rug These electrons get stored in your body, making you carry a (-) charge These electrons get stored in your body, making you carry a (-) charge When you touch a doorknob these electrons will move to the more (+) knob When you touch a doorknob these electrons will move to the more (+) knob You feel this movement as a shock! You feel this movement as a shock!

18. Do some objects allow electrons to flow faster than others? YES - some conduct electricity (electron flow) easily YES - some conduct electricity (electron flow) easily Metals (ex: copper) Metals (ex: copper) That is why wires are made of metal! That is why wires are made of metal! What types of objects don’t allow electrons to flow as easily? What types of objects don’t allow electrons to flow as easily? Rubber Rubber This is why we cover wires with rubber…so the charge running through the wires won’t transfer to your body… This is why we cover wires with rubber…so the charge running through the wires won’t transfer to your body… And shock you!

19. So in summary…what is electricity? Electricity is a form of energy that consists of a current of electrons (-) that flow from areas of high concentration (very negative) to low concentration (+). This current is capable of “doing work” for us.

20. EXIT SLIP Using the 1 st law of thermodynamics in your explanation, describe what happens to energy that is stored in a battery and then used to light up a flashlight. Using the 1 st law of thermodynamics in your explanation, describe what happens to energy that is stored in a battery and then used to light up a flashlight.