Changes between Version 16 and Version 17 of ElectricalIntroduction

Timestamp:

Aug 21, 2017, 11:43:11 AM (8 years ago)

Author:

David Albert

Comment:

--

ElectricalIntroduction

@@ -6 +6 @@
 === Batteries ===
 [[Image(sla_battery.jpg,right,15%,nolink)]]
-Batteries have two electrical ''terminals'' and chemicals between them.  The terminals and chemicals are chosen so that they can react chemically, for the reaction to work, one terminal needs to lose electrons and the other needs to gain them.  So when electrons can move from one terminal to the other, the chemical reaction proceeds.  Normally, the battery terminals are separated by air which resists the flow of electrons, but if the terminals are connected together with a wire or other material that allows electrons to flow, the reaction proceeds as long as electrons flow from one terminal to the other.
+Batteries 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.
 
 * The battery terminal that supplies electrons is called the ''negative'' terminal and is usually marked with a black color or '-' sign.
 * The battery terminal that consumes electrons is called the ''positive'' terminal and is usually marked with a red color or '+' sign.
 
-Batteries can be made from a wide variety of chemical reactions.  You can make a battery yourself 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].  There are two main types of batteries:
+There are two main types of batteries:
 * Primary: disposable batteries that you throw away when their chemicals have fully reacted and can't make electrons flow anymore (battery is fully discharged)
 * Secondary: rechargeable batteries where if you force current to flow through the battery in the reverse direction after the battery is discharged, the chemical reactions reverse themselves (the battery is re-charged) so it can make electricity flow again.
 Common 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.
 
+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].  
+
 FRC 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.
 
 For more information and details on batteries, see [http://www.edu.pe.ca/gray/class_pages/krcutcliffe/physics521/22current/applets/Electrical%20energy%20and%20electrical%20potential.htm here] and [http://www.mpoweruk.com/chemistries.htm here].
-
 
 === Voltage === 
@@ -29 +30 @@
 
 * When you get a static shock, such as touching a doorknob in the winter, you are feeling thousands of volts! 
-* Try tasting (with your tongue) the terminals of a 9v battery to see how 9v feels (this is not dangerous, but will catch your attention)
+
+*Exercise: 
+   * Materials needed: rectangular 9v battery, tongue, courage
+   * Activity: Taste (with your tongue) the terminals of a 9v battery to see how 9v feels (this is not dangerous, but will catch your attention)
 
 == Multimeter ==