* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Exponential Growth/Decay
Survey
Document related concepts
Ground (electricity) wikipedia , lookup
Buck converter wikipedia , lookup
Thermal runaway wikipedia , lookup
Opto-isolator wikipedia , lookup
Electrical substation wikipedia , lookup
Stray voltage wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Voltage optimisation wikipedia , lookup
Rectiverter wikipedia , lookup
Electrification wikipedia , lookup
Surge protector wikipedia , lookup
Power engineering wikipedia , lookup
History of electric power transmission wikipedia , lookup
Transcript
P110/120 Exam 2 AVG. 81.7 = 71.0% 12 Frequency 10 8 6 Frequency 4 2 0 45 60 75 Bin 90 110 Climate Change • What is the greenhouse effect? • What are some common green house gases? • Where is the carbon and how much gets exchanged per year? • Why do we not have a definitive answer about how hot we will get? • Behaviour of complex systems (tipping points etc.) Absorption by the Atmosphere http://en.wikipedia.org/wiki/Image:Atmospheric_Transmission.png Sediments and sedimentary Rocks could account for another 6x107 Petagrams! (www.physicalgeography.net/9r.html) http://www.whrc.org/carbon/ (Woods Hole Research Center) http://www.whrc.org/carbon/ (Woods Hole Research Center) H&K Fig. 9.6: Feedback (positive and Negative) “Butterfly effect” in complex systems CO2 Concentrations and Temperature Change Note that total temperature change across several ice ages was only about 12oC or about 22oF. Next summary will look at this: These doctors say yes the warming is there, but claim that there is no evidence that the warming is anthropogenic. Why might you be skeptical of this article? Robinson et al. J. Phys. Surg. 12, 79-90 (2007) 10 ppm ozone at ~ 50 km compared to 40 ppb ozone in the troposphere! http://www.mardiros.net/atmosphere/atmosphere_structure.html Ozone levels at Halley Bay station (Antarctica) http://www.atm.ch.cam.ac.uk/tour/part2.html TOMS Satellite movie (Total Ozone Mapping Spectrometer) http://www.atm.ch.cam.ac.uk/tour/anim_toms.html TOMS Satellite movie (Total Ozone Mapping Spectrometer) http://www.atm.ch.cam.ac.uk/tour/part2.html Montreal Protocol (1987-9) http://en.wikipedia.org/wiki/Montreal_Protocol Thermal Pollution • Remember, all energy production eventually leads to thermal energy being dumped into the environment. • I once had a colleague who claimed this was a strong argument against having unlimited cheap power (as might come from nuclear fusion). How does this compare to the problem of global warming (i.e. to the energy coming from the sun)? Thermal Pollution: Local water sources US Electrical power Look at the text, which Shows an interesting Distinction between Utility producers and Non-utility producers In terms of this mix. (p 319) http://www.eia.doe.gov/fuelelectric.html Cooling towers Basics of electricity • There is a force other than gravity that acts “at a distance” (and is stronger). • This force can be attractive or repulsive • “Static Electricity” comes in two flavours; we call these positive and negative (like charges repel, unlike charges attract). • At least some of the charges in metals are very mobile. • The force is stronger if charges are closer. • We can define a potential energy associated with the relative location of charges Basics of electricity (cont.) • The basics on the previous slide form the basis for all of our electrical technology! • We measure charge in Coulombs (6.24x1018 elementary charges) • In electrical circuits, you have an “electromotive force” that provides the “push” (V: VOLTAGE, measured in VOLTS, a potential energy difference per unit charge 1 V = 1J/1 Coulomb) • Moving charges carry the energy (I: current, measured in AMPS 1 A =1Coul/sec). • Power = I V (1 watt = 1volt*1 Amp) • The ratio of voltage to current is called the resistance of the circuit – OHM’s Law: V=IR (R measured in OHMS, W) Batteries Ohm’s Law • The ratio of voltage to current in a circuit (or circuit element) is equal to the resistance of that circuit (or element) R=V/I V=IR I = V/R • R is measured in OHMS (W) 1W= 1V/1A. Series and Parallel Circuits Series circuit: Current is the same in all elements (voltages add) Parallel circuit: Voltage is the same in all elements (Currents add) US Electrical Power Generation North American Power Plants http://en.wikipedia.org/wiki/Electric_power_transmission US Electrical power http://www.eia.doe.gov/cneaf/electricity/epa/epa.pdf#page=15