ed/gc 595 – earth system science: inquiry across scientific disciplines dr. dave donovan,...
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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
• 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://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
• 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
Small Current, Large Voltage
Similar to water drop dropped from large height.
Little Damage (Work) done!
Large Current, Large Voltage
Similar to water flowing on the ground from a great height.
Significant Damage (Work) done!
• 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.