What causes lightning?

1. What causes lightning?

2. What causes lightning • To understand lightning we first have to understand a bit about atoms and elements. • What is an atom made up of?

3. atoms • Atoms are made up of: • Electrons – negatively charged, orbit the nucleus. • Protons – positively charged, contained within the nucleus. • Neutrons – neutral charge (no charge) contained within the nucleus.

4. Electrons • Electrons move freely around the nucleus • Their movement is very complicated • Because they are not bound to the nucleus they can actually transfer from one atom/molecule to another • Some elements like to give up electrons while others like to gain electrons. • Metals tend to have electrons loosely bound to them allowing transfer of electrons from atom to atom

5. Positive and negative charges • Two atoms with the same charge (both positive or both negative) repel each other • Two atoms with opposite charges (one positive one negative) attract each other. • The same can be said on a larger scale, if an object has an overall negative charge it will be attracted to positively charged objects and repel other negatively charged objects.

6. Static electricity • We are going to explore static electricity • Static electricity • Static electricity is the buildup of charge (either positive or negative) within or on the surface of an object • You build up static electricity when you scuff your shoes on carpet, it is discharged when you shock someone.

7. Activity instructions • We will be performing a few different experiments to create static electric charge • Find a group of 2-3 (or I will find one for you) • You will collect the following materials (not yet): • Scotch tape – 2 pieces to start • Metre stick • Two pop cans • Two styrofoam cups • Balloon or pvc(plastic) pipe

8. Activity instructions • Once you have your materials: • Make two labels with a corner of paper • One should say T for top • One should say B for bottom • Put one label on each piece of tape at the end • Stick the tape together, sticky side to smooth side, make sure the piece labelled T is on top and B is on bottom • Take the pieces of tape together and stick them to your meter stick.

9. Activity instructions • Now that you have your tape stuck to a meter stick you can keep that meter stick laying across the lab bench. • Take your balloon or PVC pipe, move it close to the pieces of tape • Record your observations • Rub your balloon/pvc against your hair or a piece of fur/cloth • Move your object close to the two pieces of tape • Record your observations • Do your best to explain your observations based on what we have learned today

10. Activity instructions • Next take your pop cans and tape them (with new tape) to styrofoam cups

11. Activity instructions • Take one can and move it close to the pieces of tape, be sure to hold only by the styrofoam cup • Record your observations • Put both cans together so their bottoms are touching. Label each can as either can 1 or can 2 • Have one member of the group hold the styrofoam cups so they do not fall over • Do not touch the cans themselves at any point or you must re-start • Rub your balloon/pvc against fur/cloth/hair and move it close to the top of can 1 nearest to the side with the tab • While this is being done have one member of your group move the other can away so they are no longer touching.

12. Activity instructions • Take each can and have them interact (separately) with your two pieces of tape • Record your observations for each can • What do you think happened/is happening? • Join another group who is finished with the previous steps. • One group will take their cans and touch them, then set them back down. • Touch each groups can 1 together then separate them. Be sure to only touch the styrofoam cup. • Have each can interact with the pieces of tape (remember only touch the styrofoam) • Record your observations

13. Continue your experiment • Use either balloons or the hollow PVC pipes as they are better than the solid rods.

14. What happened? Stage 1

17. Electron affinity • Tendency of an element to donate or receive electrons.

18. Triboelectric series • Tendency of an object to donate electrons or receive electrons. • Higher on the list give up electrons • Lower on the list receive electrons • Ex. If copper is rubbed against wool copper will gain electrons while wool will give up electrons • Ex. If copper is rubbed with polyester polyester will gain electrons and copper will give up electrons

19. Static electric charge • Charging by friction: • Rubbing two objects together to create a transfer of electrons • See the triboelectric series picture • Charging by induction: • Charge is induced by placing a charged object near a neutral object. Electrons are pushed or pulled from one side of an object to another. • Charging by conduction: • Charge is transferred from one object to another through direct contact • The overall charge remains the same but is spread over two objects.

20. Conductors and insulators • A conductor is something that allows electrons to move freely • Example: the pop cans we used allowed us to induce charge by having something strongly charged near them. This would not work with two non-conductors • Wires in electrical cords are good conductors of electricity • An insulator is something that does not allow electrons to move freely • Ex. Our balloons or plastic rods can build up charge on their surface in just one place because the electrons can’t move from one spot to another • The rubber around an electrical wire insulates preventing loss of electrons (and getting a good shock!) to the environment

21. So how does lightning occur? • https://www.weathervideohd.tv/wvhd.php?mod=detail&asset=1091 • http://www.mirror.co.uk/news/world-news/force-nature-lightning-strikes-volcano-5344072

22. History and perspectives • Ancient Greeks thought lightning was a weapon used by Zeus to attack his enemies • Thought of places where lightning struck as being sacred • Would erect temples at these sites sometimes • Norse mythology associates lightning with Thor (yup the same one who shows up in the avengers!) who again used lightning as a weapon • Hindu’s also associated lightning with one of their gods who used it as a weapon

23. History and perspectives • In Africa one tribe in particular believes that lightning comes from a lightning bird-god • Their medicine men still perform ceremonies to keep storms away from them • In areas of Russia they would try to summon rain by imitating a storm • In Europe they would ring church bells to try to scare away the thunder and lightning

24. History and perspectives of electricity • Thales of Miletus ~600BC • Greek philosopher • Discovered static electricity by rubbing amber and fur together, he found amber could then attract light objects such as feathers • Believed because movement was happening on its own the amber and feather were in fact alive (so when did life begin?) • That’s about it! Nothing was done with electricity for a very long time after this • The Greek word for amber was elektron

25. William Gilbert ~ 1600 • First use of the word electricus • Made the first electroscope • Instrument able to detect static electric charge

26. Benjamin Franklin - 1750 • Came up with the idea to fly a kite in a lightning storm to show that lightning is actually a form of electricity. • Showed lightning is electricity • Invented lightning rods • Allow electricity to safely discharge into the ground through a wire

27. Michael faraday 1791-1867 • Demonstrated that a magnetic field can produce an electric field • https://www.youtube.com/watch?v=FehUCQKKRwo • Also found that magnetic fields can rotate light- called the faraday effect • https://www.youtube.com/watch?v=XhU-nNiAgtI

28. George Ohm – 1690-1746 • Discovered the relationship between current, voltage and resistance • Alesandro Volta - 1799 • Showed that electricity could be produced by chemical reactions • Invented the first type of battery • Andre-Marie Ampere – 1775-1836 • Developed theories about the relationship between electricity and magnetic fields

29. Thomas Edison 1847-1931 • Regarded as one of the most prolific inventors ever. • However most of his inventions were actually things his employees invented • Made great use of Nikola Tesla to improve direct current (DC)

30. Nikola Tesla 1856-1943 • Worked for Thomas Edison in his early career • Invented alternating current electricity (AC) • More efficient than direct current • Had a concept for wireless electricity • Thought he could power the whole world wirelessly • https://www.youtube.com/watch?v=MgBYQh4zC2Y • Very fun guy to research in your spare time

31. First nations perspective • Many First Nations have a story about Thunderbird • Thunderbird is an eagle-like bird, it’s coming announces spring • Both a spiritual and physical being • It’s eyes blink lightning and has a voice of thunder • After the first lightning and thunder of spring elders in some First Nations begin the first sweat lodge ceremonies of the year. • This is still practiced by some traditional knowledge keepers • It was believed that lightning striking the ground awoke plants to grow and produce

32. What is static electricity used for today? • Pollution control: • Smoke particles are negatively charged as they exit • Collecting plates lining the smokestack collect the pollutants

33. Other uses • Electrostatic spray painting • Target material is charged • A dry form of paint is given the opposite charge and sprayed • Advantages • Uses less paint • Gives more even coverage

34. Circuit types • Open circuit: Any circuit which is not complete, there is no possible path for the electricity to flow completely through the circuit • Closed circuit: A complete circuit, it allows electricity to flow from an energy source and eventually runs back to that same energy source • Short circuit: A circuit which allows electricity to flow from the positive to negative ends of a power source while bypassing all functional parts of the circuit. This is typically not done on purpose. • Note: a short circuit is a type of closed circuit

35. Circuit types • Parallel circuit: a circuit where there is more than one possible path for the electricity to flow. • Series circuit: a circuit where there is only one possible path for the electricity to flow. • Combination circuit: Combination circuits contain both parallel and series sections.

36. Circuit 1: • When the battery is attached is this a: • Open circuit • Closed circuit • Short circuit • Is the circuit a: • Parallel circuit • Series circuit • Combination circuit

37. Circuit 2: • When the battery is attached is this a: • Open circuit • Closed circuit • Short circuit • Is the circuit a: • Parallel circuit • Series circuit • Combination circuit 2 2 1 1

38. Circuit 3: • When the battery is attached is this a: • Open circuit • Closed circuit • Short circuit • Is the circuit a: • Parallel circuit • Series circuit • Combination circuit

39. Circuit 4: • When the battery is attached is this a: • Open circuit • Closed circuit • Short circuit • Is the circuit a: • Parallel circuit • Series circuit • Combination circuit

40. Circuit 5: • When the battery is attached is this a: • Open circuit • Closed circuit • Short circuit • Is the circuit a: • Parallel circuit • Series circuit • Combination circuit 1 3 5 1,2,3,4,5 2 4

41. Circuit 6: • When the battery is attached is this a: • Open circuit • Closed circuit • Short circuit • Is the circuit a: • Parallel circuit • Series circuit • Combination circuit B E D C A

42. Circuit 7: • When the battery is attached is this a: • Open circuit • Closed circuit • Short circuit • Is the circuit a: • Parallel circuit • Series circuit • Combination circuit

43. Is this a(n): • Open circuit • Closed circuit • Short circuit • Is the circuit a: • Parallel circuit • Series circuit • Combination circuit

44. Voltage, resistance and current • Voltage • Difference in charge between two points - measured in Volts (V) • The difference in charge is what causes electrons to move • Current • Measures the flow of electrons through a circuit - measured in amperes (A) • Resistance • Ability of any material to resist the flow of electrons – measured in Ohms (Ω)

45. Relationships • What is the voltage you recorded when there was just 1 light hooked up? • Now look at the second table (where you had two lights connected) What was the total voltage? What was the voltage of light 1? What was the voltage of light 2? • You can look at these for each set of lights which were hooked up.

46. Voltage • The total voltage should equal the voltage across each light added together • This should roughly equal the voltage of your batteries (each battery is 1.5 volts, 4 batteries = 6 volts if they were brand new batteries)

47. Resistance in series circuits • Add up the resistance of lights 1 and 2. How does this compare to the resistance of 1+2? • You can look at the same for each of the sets of batteries

48. Resistance in series circuits • The total resistance should roughly equal the resistance across the individual lights, much in the same way as voltage adds up. • Parallel circuits are different, to find total resistance of a parallel circuit: 1 = 1 + 1 + 1 + 1 + 1 Don’t worry you won’t have to calculate this. What it means though is that the resistance when there are 5 lights in parallel is MUCH LOWER than the resistance of a series circuit with those same 5 lights. R(total) R1 R2 R3 R4 R5

49. Current in a series circuit • The current in a series circuit is the same at all points. • The current depends on the total resistance of the circuit, not each individual resistance.

50. Relationship between resistance, voltage and current • Now look at the graph you constructed. • You should have found in your data that voltage remained relatively constant • It is our controlled variable (the battery determined the voltage) • As resistance went up (more lights) current went down. • When you have to run up 5 hills you will pace yourself and run slower than if you only have to run up 1 hill. Electrons pace themselves in much the same way.