1. Static Electricity

2. Electricity Unit In this unit we will cover a number of specific topics on static electricity, current, circuits and calculations of energy. This unit covers important topics from chapters 9-12 in your textbook. Please remember to complete any practice problems for homework if not finished in class on the day they are assigned.

3. Recall the following: #1 Elements on the Periodic Table are composed of atoms. These atoms are composed of a combination of Protons, Neutrons, and Electrons.

4. Recall the following: #1 Electrons have an attraction to the nucleus (Protons/Neutrons). The level of attraction differs between elements. Some of the outer most electrons are strongly attracted, others are weakly attracted. Some of the outer most electrons are strongly attracted, others are weakly attracted. For certain groups of elements ( two metals bonded) electrons are free to move (electron cloud). Copper-Cu

5. Recall the following: #2 Neutral objects have an equal number of protons and electrons. When substances lose electrons, they become positively charged ( +ve ) When they gain electrons, they become negatively charged ( -ve ) Electrons are the only thing able to transfer/move between objects (atoms).

6. Recall the following: #2 Electricity- The flow of electrons through a medium (for example: power lines, air, etc…) caused by an imbalance of charge, and the attraction of particles with opposing charges. Generating an imbalance (with the proper conditions) will lead to the flow of electrons (electricity)

7. Generating a charge A ranking can be made of items and the type of charge they generate when two are rubbed together. This is known as the triboelectric series. Weak attraction to electrons Strong attraction to electrons AcetateEbonite GlassPolyethylen e (plastic) WoolCarbon Human HairCopper CalciumNickel MagnesiumRubber LeadSulfur SilkPlatinum AluminumGold Zinc Cotton Weak: become +ve Strong: become -ve What would the charge be on each item, if you were to rub a silk scarf on a plastic ruler?

8. Generating a charge A ranking can be made of items and the type of charge they generate when two are rubbed together. This is known as the triboelectric series. Weak attraction to electrons Strong attraction to electrons AcetateEbonite GlassPolyethylen e (plastic) WoolCarbon Human HairCopper CalciumNickel MagnesiumRubber LeadSulfur SilkPlatinum AluminumGold Zinc Cotton Weak: become +ve Strong: become -ve What would the charge be on each item, if you were to rub nickel with human hair?

9. Static Charge Generated through the movement of electrons. In the previous example the wool scarf will lose electrons and the plastic ruler will gain electrons, if the two rub together. This action has created a static charge. Charged objects are said to have Static Electricity- electricity that is stationary or at rest. Depending on the type of charged material, the charge generated may move freely (as in a conductor), or be unable to move (as in an insulator)

10. Conductors and Insulators Insulators- When you give a balloon a charge, it stays in one place (‘static’). The material the balloon is made of will not let the charge(electrons) move around throughout the substance. This is called being an insulator (it insulates the charge, keeps it in one place). Most non- metals are insulators. Rubber balloon vs. metal balloon

11. Conductors and Insulators Conductors- Some materials allow a charge (electrons) to spread out through the entire substance. These are called conductors. Most metals are conductors. Conductors are used to make electrical wires because of the fact they will let a charge pass through them. Rubber balloon vs. metal balloon

12. Read pages 292-294, 296-297 Answer #1-4 on page 300 Answer #1-4 on page 300 To Review

13. The Law of Attraction and Repulsion Charged objects fall into two categories: Category A objects repel any other objects in Category A Category B objects repel any other objects in Category B Category A objects attract Category B objects Like charges repel and unlike charges attract

14. The Law of Attraction and Repulsion To test for charge, an electroscope can be used

15. sphere metal rod metal leaves + – Negative charges move away from sphere

16. How are neutral objects attracted? Certain types of neurtal objects are attracted to charged objects In these cases, the electrons within a substance will be attracted or repelled from an adjacent object, creating a temporary ‘pole’. In the example on the right, a negatively charged balloon causes electrons in the wall to be repelled. This leaves an overall positive charge in the location of the balloon.

17. To Review Read pages 301-303 and answer questions #1-5 on page 306

18. http://www.scetv.org/education/ntti/pdf/1999pdf/Wie ngesElecA1.pdf