Changes between Version 17 and Version 18 of ElectricalIntroduction


Ignore:
Timestamp:
Aug 23, 2017, 8:26:02 AM (8 years ago)
Author:
David Albert
Comment:

--

Legend:

Unmodified
Added
Removed
Modified

  • ElectricalIntroduction

    v17 v18  
    22[[Image(https://i.pinimg.com/originals/eb/41/75/eb4175c1059a1b669b96eaed29526660.jpg, 30%)]]
    33
    4 Robots need power and most robots, including our FRC robots draw their power from energy stored in an electrical battery.
    5 
    64=== Batteries ===
    75[[Image(sla_battery.jpg,right,15%,nolink)]]
     6Robots need power and most robots, including our FRC robots draw their power from energy stored in a battery.
     7
    88Batteries have two metal electrical ''terminals'' and chemicals called ''electrolyte'' between them.  The terminals and chemicals are chosen so that they can react with each other chemically.  In order for the reaction to take place, one terminal must lose electrons and the other gain them.  When electrons are able to move from one terminal to the other, the chemical reaction proceeds; when no electrons can flow, the chemical reaction stalls.  Normally, the battery terminals are separated by air which resists the flow of electrons, but if the terminals are connected together with wire or other electrically conductive material, electrons flow and the chemical reaction proceeds until the chemicals are all fully reacted (consumed).  When the chemicals are fully reacted, the battery is considered drained.
    99
    … …  
    1616Common commercial batteries include different chemical compositions: carbon-zinc, alkaline, lithium, [https://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery lead-acid], etc. and different sizes including: [https://en.wikipedia.org/wiki/AA_battery AA/penlight], [https://en.wikipedia.org/wiki/D_battery D/flashlight], [https://en.wikipedia.org/wiki/Nine-volt_battery 9V/radio], [https://en.wikipedia.org/wiki/Lantern_battery 6V/lantern], and a wide range of custom sizes.  Batteries vary widely in size, capacity, and characteristics.  In general, the larger the battery, the more chemicals it contains and the more electrical energy it can generate through the chemical reactions. The chemistry and construction determine whether the battery is disposable or rechargeable.
    1717
    18 Batteries can be made using a wide variety of chemical reactions.  You can make a battery at home using a [http://www.wikihow.com/Create-a-Potato-Battery potato] or a [https://www.scientificamerican.com/article/generate-electricity-with-a-lemon-battery/ lemon]. 
     18Batteries can be made using a wide variety of chemical reactions.  You can make a battery at home using a [http://www.wikihow.com/Create-a-Potato-Battery potato] or a [https://www.scientificamerican.com/article/generate-electricity-with-a-lemon-battery/ lemon] (see exercise under multimeter below). 
    1919
    2020FRC competition robots use large re-chargeable [http://www.andymark.com/power-patrol-sla1116-12-volt-18ah-batteries-2-pack-p/am-3062.htm lead-acid batteries].  Team 2537 also uses [http://www.batterysharks.com/12-Volt-7-Amp-Sealed-Lead-Acid-Battery-p/12V-7AH_B12-7.htm smaller lead-acid batteries] to power lighter duty robots like peanut bots.  All of these batteries are sealed so the acid/electrolyte doesn't get out and are called Sealed Lead Acid (or SLA) batteries; they also store a lot of energy and should be treated with respect.
    … …  
    5454* Exercise: Measure the voltage of several different types and sizes of batteries
    5555    * Measure a 9v battery, AA battery, robot SLA battery
     56
     57* Exercise: Make a [https://www.thetech.org/sites/default/files/pdfs/Science-Labs/SimplicityElectricity_Post_Lab-Lemon_Battery.pdf lemon battery] for details on how it works see [https://en.wikipedia.org/wiki/Lemon_battery here]
     58    * Materials needed: multimeter, knife, Lemon, copper penny (preferably minted before 1982) or copper wire, galvanized steel washer or nail
     59    * Activity:
     60         * cut a slit at each end of the lemon with the knife
     61         * slip the penny (or copper wire) half-way into one slit
     62         * slip the washer (or nail) half-way into the other
     63         * use your multimeter to measure the voltage between the penny and the washer (should be nearly 1V)
     64    * What happened: lemon juice is acidic and reacts with the copper penny and the zinc-plated washer.  The reaction with the zinc results in extra electrons at the washer giving it a negative charge; the reaction with the copper yields hydrogen ions leaving it positively charged.  If a conductive path (circuit) exists from the washer to the penny, as electrons flow through the circuit, they allow the zinc-lemon reaction and the copper-lemon reaction to proceed and you've made electricity flow!
     65    * Bonus activity (ask for help): Use lemon-batteries to provide power for an LED light (you might need a few in series)
    5666
    5767=== Current ===