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Making connections with math and basic electricity, and electronics
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Why is math important? Read the article “Math Mistakes in History: The Mars Climate Orbiter” http://threesixty360.wordpress.com/2007/11/14/math-mistakes-in-history-the-mars-climate-orbiter /“Math Mistakes in History: The Mars Climate Orbiter” http://threesixty360.wordpress.com/2007/11/14/math-mistakes-in-history-the-mars-climate-orbiter / Explain what went wrong with the Mars Climate Orbiter.
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On 9/23/On 9/23/99, $125,000,000 Mars Climate Orbiter entered Mars’ atmosphere 100 km lower than planned and was destroyed by heat. 99, $125,000,000 Mars Climate Orbiter entered Mars’ atmosphere 100 km lower than planned and was destroyed by heat. 1 lb = 4.45 N “This is going to be the cautionary tale that will be embedded into introduction to the metric system in elementary school, high school, and college science courses till the end of time.”
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What is scientific Notation? Scientific notation is a way of expressing really big numbers or really small numbers. It is most often used in “scientific” calculations where the analysis must be very precise.
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Why use scientific notation? For very large and very small numbers, these numbers can be converted into scientific notation to express them in a more concise form. Numbers expressed in scientific notation can be used in a computation with far greater ease. Mass of Proton:.00000000000000000000000167 grams Number of electrons passing by a point in a circuit: 6250000000000000000 electrons per second
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Scientific notation consists of two parts: A number between 1 and 10 A power of 10 N x 10 x Are the following in scientific notation?
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Changing standard form to scientific notation.
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To change standard form to scientific notation… Place the decimal point so that there is one non-zero digit to the left of the decimal point. Count the number of decimal places the decimal point has “moved” from the original number. This will be the exponent on the 10. If the original number was less than 1, then the exponent is negative. If the original number was greater than 1, then the exponent is positive.
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Example 1 Given: 289,800,000 Use: 2.898 (moved 8 places) Answer: 2.898 x 10 8
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Example 2 Given: 0.000567 Use: 5.67 (moved 4 places) Answer: 5.67 x 10 -4
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Practice Use the link below to practice converting standard form to scientific notation. Converting to Scientific Notation
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Changing scientific notation to standard form.
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To change scientific notation to standard form… Simply move the decimal point to the right for positive exponent 10. Move the decimal point to the left for negative exponent 10. (Use zeros to fill in places.)
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Example 3 Given: 5.093 x 10 6 Answer: 5,093,000 (moved 6 places to the right)
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Example 4 Given: 1.976 x 10 -4 Answer: 0.0001976 (moved 4 places to the left)
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Practice Use the link below to practice converting scientific notation to standard form. Converting to Standard Form
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Even More Practice Below is a list of links to games and activities all having to do with scientific notation. http://www.aaamath.com/dec71i-dec2sci.html http://janus.astro.umd.edu/cgi-bin/astro/scinote.pl http://www.sciencejoywagon.com/physicszone/lesson/ 00genral/dectosci.htm http://www.sciencejoywagon.com/physicszone/lesson/ 00genral/dectosci.htm
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Now take the quiz to test your scientific notation skills! Click on the link below to take the quiz and then use the answer key for the correct answers. Quiz Answers
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Metric Prefixes
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I can rearrange equations to solve equations for specified variables. What is the equation for solving for speed? Can you rearrange the equation to find distance? Can you rearrange the equation to find time?
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The CrickSAT Mission Reflection: Write a reflection paragraph that includes your understanding of the following questions. The CrickSAT Mission data analysis relies upon your ability to collect the data, put into its appropriate forms and to calibrate the information correctly. Based upon what you have learned about basic math in the first lesson, explain the importance of being able to calculate and use basic mathematics correctly. End of Importance of Math Basics
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Connecting Satellites and Electronics All you need to be an inventor is a good imagination and a pile of junk. -Thomas Edison
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To understand electronics we must review basic electricity. What is Electricity? Everything is made of atoms There are 118 elements, an atom is a single part of an element Atom consists of electrons, protons, and neutrons
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Electrons (- charge) are attracted to protons (+ charge), this holds the atom together Some materials have strong attraction and refuse to loss electrons, these are called insulators (air, glass, rubber, most plastics) Some materials have weak attractions and allow electrons to be lost, these are called conductors (copper, silver, gold, aluminum) Electrons can be made to move from one atom to another, this is called a current of electricity.
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Surplus of electrons is called a negative charge (-). A shortage of electrons is called a positive charge (+). A battery provides a surplus of electrons by chemical reaction. By connecting a conductor from the positive terminal to negative terminal electrons will flow.
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In your CricketSAT Mission Notebook In the Electronics Tab Create a Table to organize the variables and specific characteristics of each. Always put your name and date at the top of your table. QuantityResistanceCurrentVoltage Definition Symbol/varia ble equation Unit of measure
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How you should be thinking about electric circuits: Voltage: a force that pushes the current through the circuit (in this picture it would be equivalent to gravity)
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Voltage A battery positive terminal (+) and a negative terminal (-). The difference in charge between each terminal is the potential energy the battery can provide. This is labeled in units of volts. Water Analogy
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Current: the actual “substance” that is flowing through the wires of the circuit (electrons!) How you should be thinking about electric circuits:
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Current Uniform flow of electrons thru a circuit is called current. WILL USE CONVENTIONAL FLOW NOTATION ON ALL SCHEMATICS
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Resistance: friction that impedes flow of current through the circuit (rocks in the river) How you should be thinking about electric circuits:
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Resistance All materials have a resistance that is dependent on cross- sectional area, material type and temperature. A resistor dissipates power in the form of heat
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Ohm’s Law I = V / R Georg Simon Ohm (1787-1854) I= Current (Amperes) (amps) V= Voltage (Volts) R= Resistance (ohms)
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Ohms law defines the relationship between voltage, current and resistance. These basic electrical units apply to direct current, or alternating current. Ohm’s Law is the foundation of electronics and electricity. This formula is used extensively by electricians. Without a thorough understanding of “Ohm’s Law” an electrician can not design or troubleshoot even the simplest of electronic or electrical circuits. Ohm established in the late 1820’s that if a voltage was applied to a resistance then “current would flow and then power would be consumed”.
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Ohm's law magic triangle Voltage = E or V Current = I Resistance = R
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Ohm’s Law
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If you know E and I, and wish to determine R, just eliminate R from the picture and see what's left:
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If you know E and R, and wish to determine I, eliminate I and see what's left:
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if you know I and R, and wish to determine E, eliminate E and see what's left:
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The force or pressure behind electricity variable
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Symbol and Unit Ω = Ohm
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milliamp or just mA
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As a milliampere (milliamp or just mA) is 1/1000th of an ampere, we can convert mA to Amps by just dividing by 1000. Another way is to take the current in mA and move the decimal to the left three places to accomplish the division by 1000. Here's the scoop: 275 mA / 1000 = 0.275 Amps Note that the decimal in 275 is to the right of the 5, and it's written as 275.0 (with a 0 added to show where the decimal is). Moving the decimal to the left three places gets up to.275 Amps, but we usually hang a 0 in front of the decimal. To convert Amps to milliAmps, just multiply by 1000 or move the decimal to the right three places. Just the opposite of what we did here to convert the other way. Conversions of units
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Power Definition Variable Equation unit Depends on
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Electrical Power Power is the rate of using or supplying energy: Power = Energy / Time Power is measured in watts (W) Energy is measured in joules (J) Time is measured in seconds (s)
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Electrical Power Electronics is mostly concerned with small quantities of power, so the power is often measured in milliwatts (mW), 1mW = 0.001W. For example an LED uses about 40mW and a bleeper uses about 100mW, even a lamp such as a torch bulb only uses about 1W. The typical power used in mains electrical circuits is much larger, so this power may be measured in kilowatts (kW), 1kW = 1000W. For example a typical mains lamp uses 60W and a kettle uses about 3kW.
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Electrical Power Besides this basic equation for power: P = I*V remember we also have Ohm’s Law: V = I*R. Challenge: Based upon the two equations, how is power related to resistance?
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Power Definition Variable Equation unit Depends on Power is the rate of using or supplying energy P Power = Energy time Power is measured in watts (W) Energy is measured in joules (J) Time is measured in seconds (s)
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Variable
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Unit Ω = Ohm
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S.MORRIS 2006 ELECTRICAL CIRCUITS More free powerpoints at www.worldofteaching.com
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Activity Sheet should include your name, date, and the following discovery information as well as you data table and conclusion. Put in your Mission note book under the Electronics Tab. Discovery Activity: Open and Closed Circuits Purpose: Evaluate and create an open and a closed circuit. Materials: Mini light bulb, connecting wire, battery Prediction: Make a prediction of what an open and a closed circuit would be. Procedure: 1. Read all of the directions. Create a data table to record your results. Include draws and explanations. 2.Manipulate the materials in many different ways to light the light bulb. Be sure to draw and explain each trial on your data table. Conclusion: Review and analyze your data collected from the discovery activity. Write a conclusion, What is an open and closed circuit.
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Would This Work?
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The Central Concept: Closed Circuit
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circuit diagram cellswitchlampwires Scientists usually draw electric circuits using symbols;
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Simple Circuits Series circuit All in a row 1 path for electricity 1 light goes out and the circuit is broken Parallel circuit Many paths for electricity 1 light goes out and the others stay on
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Series and Parallel Circuit Activity Create an Activity Sheet for the following activity. Purpose: Describe what happens to the current in a series as more resistors are added to the circuit. Prediction: Predict what will happen to the current in a series as more resistors are added. Procedure: Read all of the directions and create a data table to organize the information. Include drawings in your table. Materials: 6 V battery, 3 light bulbs (Christmas lights will work), 6 connector wires
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Part 1 Series Circuit 1. Connect one bulb to the battery creating a closed circuit. Record the relative brightness and draw the circuit. 2. Repeat step 1 and add a second light. Record and draw. 3. Repeat step 2 and add a third light. Record and draw. 4. Remove the middle light. What happened? 5. Conclusion: Write a statement which decribes what happens to the current in a series circuit as you add more resistors (lights)?
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The current decreases because the resistance increases. Ohm’s Law says that I=V/R. The voltage in the system is constant, resistance increases. 1 2 3
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PARALLEL CIRCUIT Place two bulbs in parallel. What do you notice about the brightness of the bulbs? Add a third light bulb in the circuit. What do you notice about the brightness of the bulbs? Remove the middle bulb from the circuit. What happened?
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The CrickSAT Mission Reflection: Write a reflection paragraph that includes your understanding of the following questions. What connections can you make between Ohm’s Law and The CrickSAT Project? (purpose, importance,???)
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