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Grade 9-U2-L1-Static electricity
- 1. Introduction to Electricity •In this unit we will be studying: • Static electricity • Current electricity • Power generation.
- 2. • Did youever walk across a carpet, touch something and get a shock? That shock was caused by static electricity. The science of static electricity is called electrostatics. Static ElectricityStatic Electricity
- 3. • The word‘static’ means not moving • Static electricity means electrons are not moving along a path or not flowing (current electricity). • Rather electrons are supplied from one atom and moved onto another atom resulting in a build-up of charge. Static ElectricityStatic Electricity
- 4. Subatomic Particles Charge Location in atom proton positive (+)nucleus neutron no charge (0) nucleus electron negative (-) orbiting the nucleus
- 5. If an objecthas more electrons than protons, it is negatively charged. Electric ChargeElectric Charge # protons: 8 # electrons: 12 # protons < # electrons therefore, overall charge = negative
- 6. if an objecthas more protons than electrons, it is positively charged Electric ChargeElectric Charge # protons: 8 # electrons: 5 # protons > # electrons therefore, overall charge = positive
- 7. If an objecthas an equal number of protons and electrons, the object is neutral Electric ChargeElectric Charge # protons: 8 # electrons: 8 # protons = # electrons therefore, overall charge = neutral
- 8. Electric ChargeElectric Charge +— Law of attraction: opposite charges attract
- 9. Electric ChargeElectric Charge + — Lawof repulsion: like charges repel + —
- 10. Electric ChargeElectric Charge + — Acharged object and a neutral object will attract each other 0 0
- 11. • Electrons canbe transferred from one object to another. • For example, a neutral or positively charged object will become negatively charged if it gains electrons. Electric ChargeElectric Charge
- 12. • Similarly, aneutral or negatively charged object will become positively charged if it loses electrons. Electric ChargeElectric Charge
- 13. Only electrons (negative charges)are capable of moving from one object to another! Protons (positive charges) stay in place. Electric ChargeElectric Charge
- 14. • Conductivity isthe ability of materials to allow electrons to move freely • Materials that hold on to their electrons and do not allow them to move easily are called electrical insulators • Materials that allow electrons to change positions are called conductors Conductors & InsulatorsConductors & Insulators
- 15. InsulatorsInsulators +— + — + — +— +— + — +— In an insulator,the electrons (-) are bound tightly to the nuclei (+) so they resist movement
- 16.
- 17. ConductorsConductors + — + — + — + — + — +— + — In a conductor,the electrons are not as tightly bound to the nuclei and can therefore move away from the nuclei
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- 19. Detecting ChargesDetecting Charges •There are different instruments used to detect charged objects: – Pith Ball Electroscope – Metal Leaf Electroscope • In both instruments neutral position of leaves/ball changes when charged object is place closeby
- 20. Pith Ball ElectroscopePithBall Electroscope • A pith ball electroscope consists of a neutrally charged ball of pith (plant material) and non- conductive string and stand • When charged object brought close to ball, the ball will be attracted to it
- 21. Metal Leaf ElectroscopeMetalLeaf Electroscope • A metal leaf electroscope is more sensitive to electric charge than a pith ball electroscope • When charged object brought close to metal ball or cap, the leaves will repel each other and spread apart
- 22. Videos and PracticeQuestions • https://www.youtube.com/watch?v=yc2-363MIQs • https://www.youtube.com/watch?v=QxZ6AWLpnUw • https://www.youtube.com/watch?v=oU8Fe6846d4