Electricity

1. Applied Science III – Mr. Finau Electricity

2. What are the three types of particles in an atom? Describe each of them. • Protons – a large particle in the nucleus • Electron – a small particle revolving around the nucleus • Neutron – a large particlein the nucleus

3. What is charge? What type of charge did each particle have? • Charge – a property of particles that determines electromagnetic interaction • Proton – Positive • Electron – Negative • Neutron – neutral (lack of charge or balanced charge)

4. What is the most fundamental rule of charges? (think of a magnet) • Like charges repel – unlike charges attract • ie – protons will attract electrons, but repel other protons. Vice versa for electrons

5. In chemistry, what particle is transferred or shared during bonds? Why? • Electrons are transferred or shared • They are the smallest particles and are easily pulled away from atoms to make different types of bonds

6. What happens when you rub your socks across the carpet? Explain using electrons. • Build up static electricity – ie. Building up charge • Electrons are rubbed off of the carpet onto your socks

7. What happens if you then touch a doorknob (or some other metal object)? Explain using electrons. • You get shocked! There’s actually a small lightning bolt created • Electrons are transferred from you to the doorknob

8. What is this process called? What objects are best known for this process? • Conduction – process of transferring charge through contact between two objects • Conductors – any material that allows charge to easily pass through • Examples – steel, copper, metals in general (including metals in periodic table such as graphite, sodium)

9. Bill Nye on Static Electricity

10. What is conservation of charge? • Similar to conservation of energy… • Charge cannot be created nor destroyed – always conserved • A change in charge is created by transferring electrons; if you transfer electrons from the carpet to your socks, your socks will be negatively charged – but the floor will be positively charged

11. What happens when you rub a balloon against your hair? • Transfer electrons from your hair to the balloon • Gives balloon a negativecharge

12. Explain why your hair tends to stand on end. • If electrons are transferred from your hair, what is left? • Protons – positive charge • If there’s an abundance of positive charge on your hair, what happens? • Repel each other – push away from each other – stand on end

13. Where else in your daily lives do you use this process? • Brushing/Combing your hair • You transfer electrons from your hair – positively charged hair doesn’t stick together as much; produces more “bounce?”

14. What happens when you put the balloon against the wall? • Balloon sticks to the wall – remains in same spot • Negative charge pushedaway

15. What is this process called? • Induction - separation of charge when near an already charged object • Like charges are pushed away, leaving only unlike charges – attraction occurs keeping balloon stuck to wall

16. What kinds of materials do not allow charge to move freely? What are they called? • Examples - Plastics, Rubber, fiberglass • Insulators – any material that resists the movement of charge

17. When we brought a charged object near an insulator, how did its particles arrange? What’s this called? • Electrons are pushed away, while protons are pulled towards. • Charge Polarization – the aligning of particlescaused by an electric field • Microwaves use this togive energy (heat) to yourfood

18. How can you remove charge from an object? Where does the charge go? What’s this process called? • Touch the object – charge balances out • Discharge – excess charge moves out of object until balanced • Grounding - process of removing the excess charge on an object by means of the transfer of electrons between it and another object of substantial size

19. What causes an object to be pushed away or pulled towards a charged object? What does it depend on and how is it dependent (directly or inversely)? • Electric Force – force between two or more charged particles/objects • Directly proportional to amount of charge • Inversely proportional to distance between charges

20. How is Electric Force similar to gravity on Earth (or any planet for that matter)? How is it different? • Both are Field Forces • Electric Force can pull or push away – Gravity can only pull towards • Electric force is also a much stronger force than gravity

21. What surrounds a charged object? • Electric Field – region around a charged object where an electric force can occur

22. How is the electric field related to the force on an object? • Electric Field always exists around a charged object • Electric field causes anelectric force

23. Does the electric field increase or decrease as you move away from the object? How can you tell? • Electric field decreases as you move away • Farther away Less force Less Electric Field

24. Which direction does the electric field flow? • Outward from a positive charge and inward towards a negative charge

25. How does charge traditionally flow? What is this flow called? • Like the electric field, charge flows from positive to negative • Current – the amount of charge that passes in a given amount of time

26. What’s the difference between Direct and Alternating Current? • Direct Current – charge flows in one direction from positive to negative • Easiest form of electricity – dispensed from batteries, generators • Alternating Current – charge vibrates back and forth • Produced and dispensed by power plants; distributed through wall sockets

27. Plan for next few days Thurs – Virtual lab on Electric Fields - Virtual lab will be all online (no paper) Fri – working day Mon – Review for Quiz Tues – Quiz on Electricity

28. Electrical Circuits • Electrical Circuits are closed paths that allows electrical charges to pass through electrical elements

29. How do we represent complex electrical systems? • Circuit Diagram - a simplified conventional graphical representation of an electrical circuit

30. Example Diagrams

31. Electrical Circuit Symbols

32. What does a battery do? What is potential difference? • A battery pushes charge through a closed circuit. • Potential Difference is the voltage lost from one side of an energy source to the other. • In a 9 V battery, the potential difference is 9 V

33. What is capacitance and a capacitor? • Capacitance is the ability of a conductor to store charge • A capacitor is a conductor that stores charge • Typically two separated metal plates that hold a certain amount of charge on each plate • Can be Dangerous!!

34. What is Resistance and a resistor? • Resistance is the opposition an object has to the flow of electrical current (units - Ohms) • A resistor is technically any object that has some resistance to a circuit’s current • The resistance of an object depends on 4 things: • Length – directly proportional • Width – inversely proportional • Temperature – directly proportional • Material – depends on each substance

35. Different Way to Look at it Without a resistor With a resistor The greater the amount of resistance is similar to construction reducing the amount of lanes on a highway

36. Resistors can be arranged in two ways. What are they and how do they affect the current? • Series – resistors lined up one after the other • Current is constant through all elements • Parallel – resistors spread out in branches • Current is distributed to all branches • Draw example from simulation

37. In a series circuit, what happens if you remove a lightbulb from the circuit? Why does this occur? • All of the lightbulbs go out • A closed circuit is necessary; removing a lightbulb breaks the circuit

38. What happens to the current through a series circuit if you increase the voltage? What does this look like on the simulation? • Increase the voltage – increase the current • The electrons move through the wires quicker

39. What happens to the current the more lightbulbs you add to the series circuit? What else are you adding more of? • The more lightbulbs added… • The slower the current moves • The dimmer the lights become • Adding more lightbulbs add more resistance

40. What are the two things that current depends on? How are they dependent? What is our equation? • Current depends on Voltage and Resistance • Current is: • Directly proportional to Voltage • Inversely proportional to Resistance Ohm’s Law

41. If a 12 Volt battery is hooked up to a light bulb with a resistance of 3 Ohms, how much current is moving through the circuit? What is the current if you add another 3 Ohm lightbulb to the circuit? • I = V/R • 12/3 = 4 Amps • Total resistance is 3 + 3 = 6 • 12/6 = 2 Amps

42. A Shocking Video

43. Tutorial On Virtual Lab • Monday/Tuesday – Virtual lab on Electrical Circuits • Wed – Review for Quiz • Thurs – Quiz on Electrical Circuits • Fri – Working Day

44. Circuits Lab • Get a laptop • Take a lab handout and follow the instructions on the sheet

45. Review • Circuit diagram symbols • Voltage, Current, Resistance, Capacity • Difference between DC & AC electricity • Difference between series and parallel circuits • Difference between open and closed circuits • What does Resistance depend on? • Remember the Simulation • What did the blue dots represent? • What happens when there is no resistance in a circuit?