ED/GC 595 – Earth System Science: Inquiry Across Scientific Disciplines

Dr. Dave Donovan, Professor of Physics, NMU.Marquette, MI June 2009

Physics Standards Grades 3 - 7

• Grade 3– Changes in Motion– Light and Sound

• Grade 4– Heat, Electricity, and Magnetism

• Grade 5– Measuring Changes in Motion– Position and Motion of Objects in the Sky

Physics Standards Grades 3 – 7 (Cont)

• Grade 6– Matter and Energy– Plate Tectonics and Fossils

• Grade 7– Waves and Energy

Content Statements and Expectations for Heat, Electricity and Magnetism

http://www.michigan.gov/documents/mde/Complete_Science_GLCE_12-12-07_218314_7.pdf

Page 43 – 45

• Charge is a fundamental property of matter that indicates how the matter will behave in an electric or a magnetic field.

• Unit of Charge is the Coulomb, 1 electron has a charge of -1.6 x 10-19 C. => 1 C requires 1018 e- s

• There are two types of Charge: Positive(+) and Negative(-)

• Ben Franklin first proposed the laws of Charge– Like Charges Repel– Opposite Charges Attract

• Most objects are charged by an excess (-) or a deficiency (+) of electrons.

http://web.ncf.ca/ch865/graphics/ParabInEFld.jpeg

http://www.stneots- science.co.uk/Physics_GCSE/Physics_AQA/Physics_1B/Radiation_E_Field.GIF

E Field going from top to bottom, High Voltage to Low Voltage

http://electron9.phys.utk.edu/phys136d/modules/m7/images/Image1234.gif

B Field going into Paper

Positively Charged (+) Particle

Negatively Charged (-) Particle

http://www.windows.ucar.edu/spaceweather/images/cyclotron_animated.gif

http://blog.makezine.com/carbon%20atom.jpg

• Current is the amount of charge which moves past a given reference point in a given amount of time.

• The unit of Current is the Ampere. 1 A = 1 C/s

• Voltage is the amount of Electrical Potential Energy per unit Charge at a point.

• The unit of Voltage is the Volt. 1 V = 1 J/C.• J (Joule) is a unit of energy. • 1 J is the amount of energy a 2 kg mass has when

moving 1 m/s, or 4.186 J is the energy needed to heat 1 g of water 1˚C. (ie. 4.186 J is 1 Calorie)

• Current goes from Higher Voltage (more +) to Lower Voltage (more -).

• + Charges are repelled by Higher (+) Voltages and attracted to Lower (-) Voltages.

• - Charges are attracted to Higher (+) Voltages and repelled by Lower (-) Voltages.

• Currents are defined by the direction a (+) charge would take in a circuit.

Water Analogy of Electricity

• Current is analogous to Water Flow (ie how much water flows in the pipe?).

• Voltage is analogous to Water Pressure (ie how much energy does the water in the pipe have?).

• Resistance is the opposition to current flow. It is analogous to impediments in the pipe, debris, friction, changes in pipe diameter, etc.

http://www.windows.ucar.edu/physical_science/physics/electricity/images/circuit_analogy_water_pipes_sm.jpg

http://img.tomshardware.com/us/2006/11/03/how_notebook_batteries_work_and_why_they_blow_up/

how_batteries_work_figure02.jpg

http://www.rare-earth-magnets.com/images2/00020.jpg

Large Current, Small Voltage

Similar to water flowing on the ground.

Little Damage (Work) done!

http://www.land-by-swac.com/owen/caglesdam3.jpg

http://2.bp.blogspot.com/_rRE3wywM9G8/Rv1jdbjZ_DI/AAAAAAAAAF8/Jc2N0JTyYLc/s400/birds+on+a+wire.jpg

Small Current, Large Voltage

Similar to water drop dropped from large height.

Little Damage (Work) done!

http://image14.webshots.com/15/3/54/74/175435474pPYzHV_fs.jpg

http://images.veer.com/IMG/PIMG/FAN/FAN2050908_P.JPG

http://www.school-for-champions.com/science/images/static_sparks-finger.jpg

Large Current, Large Voltage

Similar to water flowing on the ground from a great height.

Significant Damage (Work) done!

http://www.zmescience.com/wp-content/uploads/2008/05/waterfall3.jpg

http://contentdm.library.unr.edu/cgi-bin/showfile.exe?CISOROOT=/spphotos&CISOPTR=450

http://i.pbase.com/g3/60/657460/2/58705452.lightning2a7z.jpg

• An Electrical Circuit is a collection of Electrical Elements connected together.

• Electrical Elements are Power Providers (Batteries), Power Using Devices (Lights, motors, etc), and Connective Elements (Wires).

• A circuit will have electrical current flow through it only if the circuit is complete. The circuit begins on or at a High Voltage point and it must end on or at a Low Voltage point. Often these are two parts of a Power Providing Device.

A Simple Circuit

A Simple Circuit

i (current)

High Voltage

Low Voltage

i (current)

Power Providing Power Using