1. Electricity and magnetism

2. Nobel prize: graphene Andre Geim University of Manchester Konstantin Novoselov

3. The unit of electric current is the: A)Volt B)Amp C)Coulomb D)Ohm E)Watt

4. Did you read the assignment>? A)Yes B)No

5. A superconductor is a material that: A)Has lots of electrons B)Insulates your home C)Has zero resistance D)Nobody has created yet E)Has extremely high voltage

6. Heat engines  electricity

8. The basics of electrostatics

10. What can we conclude about the signs of Q1 and Q2? A: One is "+", the other is "-" B: Both are "+" C: Both are "-" D: Both must be the same charge (but we can't tell if they're both "+", or both "-") Two equal mass balls are charged, and hang on strings as shown:

11. Two uncharged conducting spheres, A and B, are suspended from insulating threads so that they touch each other. While a negatively charged rod is held near, but not touching sphere A, the two spheres are separated. How will the spheres be charged, if at all? Sphere A Sphere B A)0 + B) - + C) 0 0 D) - 0 E) + - A B

12. An electron traveling horizontally enters a region where a uniform electric field is directed upward. What is the direction of the force exerted on the electron once it has entered the field? A) to the left B) to the right C) upward D) downward E) out of the screen

13. Pick up here Oct 14

14. If we put bunch of electrons in a box, they will A) clump together. B) spread out uniformly across box. C) make a layer on walls. D) do something else.

15. Voltage? Voltage is the energy per charge.

16. CRT: Cathode ray tube (tv)

17. Current I = = Current is the flow of electric charges. Amount of charge time

18. Why isn’t this bird toast? A)The bird understands quantum physics B)The wire has no current running through it C)The bird’s other leg isn’t touching the ground D)Wires are insulated for safety – people walk up to wires and touch them too with no problem

19. Resistance

20. IAIA IBIB Which current is bigger? A)I A B)I B C)They are the same

21. IAIA IBIB Which current is bigger? A)I A B)I B C)They are the same R r R is big resistance r is small resistance

22. Tues Oct 19 pick up here

23. Opinions about circuit stuff Are the conceptual circuit sims (PhE`T) that we’ve been playing with helpful? A)Yes B)No C)Sort of…

24. Opinions about circuit stuff What about the ones I’ve drawn on the board — helpful? A)Yes B)No C)Sort of…

25. Opinions about circuit stuff Are our exercises helping you to see how electricity ‘works’ in our lives? A)Yes B)No C)Sort of…

26. Opinions about circuit stuff Would more math help you to see what’s happening? A)Yes B)No C)Not sure

27. Opinions about circuit stuff How well do you understand voltage, current, and resistance? A)I can build a computer from scratch now B)I can explain all of the examples that we’ve been through C)I have a grasp on most of the concepts D)I might struggle if you asked me a question like “which lightbulb is brighter” in a circuit with 2 or 3 bulbs and a battery E)I’m actually kind of lost

28. Opinions about circuit stuff How much longer do you want to spend on this stuff? A)I want more time to explore and discuss with other students B)I want more instruction C)I want to move on to new stuff

29. Worksheet on circuits for next week’s hw? A)Yes please B)No! C)Just make it optional

30. Other feedback?

31. Resistance

32. Table of resistivities Material Resistivity [Ω·m] at 20 °C Temperature coefficient* [K −1 ] Referen ce Silver1.59×10 −8 0.0038 [1][2] Copper1.68×10 −8 0.0039 [2] Gold2.44×10 −8 0.0034 [1] Aluminium2.82×10 −8 0.0039 [1] Calcium3.36x10 −8 0.0041 Tungsten5.60×10 −8 0.0045 [1] Zinc5.90×10 −8 0.0037 [3] Nickel6.99×10 −8 0.006 Iron1.0×10 −7 0.005 [1] Platinum1.06×10 −7 0.00392 [1] Tin1.09×10 −7 0.0045 Lead2.2×10 −7 0.0039 [1] Mercury9.8×10 −7 0.0009 [4] Nichrome [6] 1.10×10 −6 0.0004 [1] Carbon (amorphous) 5-8×10 −4 −0.0005 [1][7] Carbon (graphite) [8] 2.5-5.0×10 −6 ⊥ basal plane 3.0×10 −3 // basal planebasal plane [9] Carbon (diamond) [10] ~10 12[11] Germanium [10] 4.6×10 −1 −0.048 [1][2] seawater2×10 −1 ? Silicon [10] 6.40×10 2 −0.075 [1] Glass10 10 to 10 14 ? [1][2] Hard rubberapprox. 10 13 ? [1] Sulfur10 15 ? [1] Paraffin10 17 ? QuartzQuartz (fused)7.5×10 17 ? [1] PET10 20 ? Teflon10 22 to 10 24 ?

33. Material Resistivity [Ω·m] at 20 °C Temperature coefficient* [K −1 ] Referenc e Silver1.59×10 −8 0.0038 [1][2] Copper1.68×10 −8 0.0039 [2] Gold2.44×10 −8 0.0034 [1] Aluminium2.82×10 −8 0.0039 [1] Calcium3.36x10 −8 0.0041 Tungsten5.60×10 −8 0.0045 [1] Zinc5.90×10 −8 0.0037 [3] Nickel6.99×10 −8 0.006 Iron1.0×10 −7 0.005 [1] Platinum1.06×10 −7 0.00392 [1] Tin1.09×10 −7 0.0045 Lead2.2×10 −7 0.0039 [1] Mercury9.8×10 −7 0.0009 [4] Nichrome [6] 1.10×10 −6 0.0004 [1] Carbon (amorphous) 5-8×10 −4 −0.0005 [1][7] Carbon (graphite) [8] 2.5-5.0×10 −6 basal plane 3.0×10 −3 // basal planebasal plane [9] Carbon (diamond) [10] ~10 12[11] Germanium [10] 4.6×10 −1 −0.048 [1][2] seawater2×10 −1 ? Silicon [10] 6.40×10 2 −0.075 [1] Glass10 10 to 10 14 ? [1][2] Hard rubberapprox. 10 13 ? [1] Sulfur10 15 ? [1] Paraffin10 17 ? QuartzQuartz (fused)7.5×10 17 ? [1] PET10 20 ? Teflon10 22 to 10 24 ?

35. Surface mount devices

36. Review… IAIA IBIB Which current is bigger? A)I A B)I B C)They are the same V

37. Review… rR voltage drop Which voltage drop is bigger? A)Across r B)Across R C)They are the same V

38. IAIA IBIB Which voltage drop is bigger? A. Across r B. Across R C. They are the same R r R is big resistance r is small resistance V

39. RR V

40. RR #2 RR Which circuit has brighter light bulbs? A)#1 B)#2 C)All light bulbs are the same brightness #1 V V

41. Which circuit has brighter light bulbs? A)#1 B)#2 C)All light bulbs are the same brightness R R R #1 #2 VV

43. Capacitor

54. Current is what kills Ordinarily skin has a resistance of 5,000,000 ohms. When wet, the resistance of skin drops by more than a factor of a thousand The body itself is very conductive (approximately salt water), typical resistance between appendages is ~ 500 ohms. The danger here is that usually we are protected with our dry skin which can get one accustomed to taking electrical risks. All it takes is for the skin to be dirty, sweaty, or damp to very significantly reduce it’s resistance (>1000x) enough to make current vary, for a given ideal voltage source, from barely perceptible to heart paralysis.

61. Review: electric fields from charges

63. Review: which way does a positive charge move in an electric field? Electric field A)Goes up B)Goes down C)Goes left D)Goes right E)Doesn’t move

64. How about a negative charge (like an electron)? Electric field A)Goes up B)Goes down C)Goes left D)Goes right E)Doesn’t move

66. What about a magnetic field? Magnetic field A)Goes up B)Goes down C)Goes left D)Goes right E)Doesn’t move

67. Force on a wire

68. Magnetic field A)up B)toward you C)away from you D)right E)No force

70. How can you measure current?

77. Sample savings for replacing an old 22 c.f. fridge with a newer model A 22 cf fridge made in this year... Uses about this much energy... Replacing with a 2001+ model saves: Replacing with a 2008+ Energy Star model saves: Replacing with a CEE Tier 3 model saves: <19762200 kWh$238 / yr. $257 / yr.$266 / yr. 1976-861700 kWh$165 / yr. $183 / yr.$192 / yr. 1987-891150 kWh$83 / yr. $101 / yr.$110 / yr. 1990-921100 kWh$73 / yr. $92 / yr.$101 / yr. 1993-00850 kWh37 / yr. $55 / yr.$64 / yr. 2001-2010600 kWh- $18 / yr.$28 / yr. 2001-2004 Energy Star (10%+ better)550 kWh-$9 / yr.$18 / yr. 2004-2008 Energy Star (15%+ better)525 kWh-$5 / yr.$14 / yr. 2008-2010 Energy Star (20%+ better)500 kWh--$9 / yr. CEE Tier 3 (30%+better)425 kWh---

78. kWh per month

81. Two bar magnets are brought near each other as shown. The magnets... A) attract B) repel C) exert no net force on each other.

82. A bar magnet is positioned below a horizontal loop of wire with its North pole pointing toward the loop. Then the magnet is pulled down, away from the loop. As viewed from above, is the induced current in the loop clockwise or counterclockwise?

83. Transformer You have a transformer with N p =6 primary windings, and N s =3 secondary windings, as shown. If V p =120 V AC, what is the voltage in the secondary circuit? A) 120 V B) 60 V C) 240 V D) 30 V V secondary

84. HIGH energy LOW energy

85. Circuit Construction Kit Clicker questions PICK THROUGH THESE…… Three activities by Trish Loeblein phet.colorado.edu 1.Introduction to Electrical circuits 2.Resistors in Series and Parallel Circuits 3.Combo Circuit Lab

86. Introduction to Electrical circuits Learning Goals: Students will be able to 1.Discuss basic electricity relationships 2.Analyze the differences between real circuits and the simulated ones 3.Build circuits from schematic drawings 4.Use a multimeter to take readings in circuits. 5.Provide reasoning to explain the measurements and relationships in circuits.

87. 4. If you build circuit A and then add a resistor as in circuit B, the light will A.Look brighter B.Look less bright C.There will no change in brightness AB

88. Resistors in Series and Parallel Circuits 1.Learning Goals: Students will be able to 2.Discuss basic electricity relationships in series and parallel circuits 3.Analyze the differences between real circuits and the simulated ones 4.Build circuits from schematic drawings 5.Use a multimeter to take readings in circuits. 6.Provide reasoning to explain the measurements in circuits.

89. 2. Which resistor will have the greatest current? A. 50  B.10  C.They have the same current

90. 3. Which resistor will have the greatest current? A.The top resistor B.The lower resistor C.They have the same current

91. 4. Which resistor will have the greatest voltage? A. The top resistor B.The lower resistor C.They have the same voltage

92. 5. Which resistor will have the greatest voltage? A. 50  B.10  C.They have the same voltage

93. 6. Which resistor will have the greatest voltage? A. 50  B.10  C.They have the same voltage

94. 7. Which resistor will have the greatest current? A. 50  B.10  C.They have the same current

95. 8. Which resistor will have the greatest voltage? A. The top resistor B.The lower resistor C.They have the same voltage

96. 9. Which resistor will have the greatest current? A. The top resistor B.The lower resistor C.They have the same current

97. 10. What will happen if the voltage of the battery is increased to 25 volts? A. The voltage across the resistor will increase B.The voltage across the resistor will decrease C.The voltage of the resistor does not change

98. 11. What will happen if the voltage of the battery is increased to 25 volts? A. The current through the resistor will increase B.The current through the resistor will decrease C.The current of the resistor does not change

99. Combo Circuit Lab Learning Goals: Students will be able to: 1.Analyze the differences between real circuits and the ideal ones, 2.Build circuits from schematic drawings, 3.Use a multimeter to take readings in circuits. 4.Provide reasoning to explain the measurements in circuits.

100. 12. What is the total resistance in this circuit? A.6.4  B.21  C.38  D.75 

101. 13. What is the total resistance in this circuit? A.6.4  B.21  C.38  D.75 

102. Faraday’s Electromagnet Lab by Trish Loeblein May 10, 2010 http://phet.colorado.edu http://phet.colorado.edu Learning Goals Activity 1: Students will be able to 1.Predict the direction of the magnet field for different locations around a bar magnet and electromagnet. 2.Compare and contrast bar magnets and electromagnets 3.Identify the characteristics of electromagnets that are variable and what effects each variable has on the magnetic field’s strength and direction. 4.Relate magnetic field strength to distance quantitatively and qualitatively 5.Compare and contrast the fields of gravity and magnets qualitatively Learning Goals Activity 2: Students will be able to: Identify equipment and conditions that produce induction Compare and contrast how both a light bulb and voltmeter can be used to show characteristics of the induced current Predict how the current will change when the conditions are varied.

103. 1.Which compass shows the correct direction of the magnet field at point A? A. B. C. D. A

104. 2.Which compass shows the correct direction of the magnet field at point A? A. B. C. D. A

105. 3.Which compass shows the correct direction of the magnet field at point A? A. B. C. D. A

106. 4.What will happen if you switch the battery so that the positive end is on the right? A. The electrons will go faster B.The electrons will go the slower C.The compass will switch directions D.The electrons will go the other direction E.Two of the above.

107. 5.What would you expect the light to do if you change the coils from 2 to 3 and you move the magnet the same speed? A.Show the same brightness B.Show less brightness C.Show more brightness

108. 6.Which would be a more strong magnet? A.A B.B C.They would be the same D.Not enough information to decide A B

109. 7.Which would be a more strong magnet? A.A B.B C.They would be the same D.Not enough information to decide A B

110. Magnetic field