Changes between Version 9 and Version 10 of ElectricalIntroduction

Timestamp:

Aug 21, 2017, 10:59:23 AM (8 years ago)

Author:

David Albert

Comment:

--

ElectricalIntroduction

@@ -21 +21 @@
 
 === Voltage === 
-The difference in electrical potential between the two terminals of a battery is measured in units of Volts (named after [https://en.wikipedia.org/wiki/Alessandro_Volta Alessandro Volta]).  Voltage is *potential* energy, like the reservoir/lake behind a hydroelectric dam; no work is being done if the water isn't flowing, but you can measure the pressure the water is exerting on the dam.  [[Image(dam_diagram.png,right,20%,nolink)]] Voltage is a potential, it represents a difference in charge, the strength of attraction between two opposite charges.  Different types of batteries use different types of chemical reactions to generate that charge potential difference.  For more information about electricity and voltage, see [https://learn.sparkfun.com/tutorials/what-is-electricity here]  
+The difference in electrical potential between the two terminals of a battery is measured in units of Volts (named after [https://en.wikipedia.org/wiki/Alessandro_Volta Alessandro Volta]).  Voltage is *potential* energy, like the reservoir/lake behind a hydroelectric dam; no work is being done if the water isn't flowing, but you can measure the pressure the water is exerting on the dam.  [[Image(dam_diagram.png,right,30%,nolink)]] Voltage is a potential, it represents a difference in charge, the strength of attraction between two opposite charges.  Different types of batteries use different types of chemical reactions to generate that charge potential difference.  For more information about electricity and voltage, see [https://learn.sparkfun.com/tutorials/what-is-electricity here]  
 
 Different [http://www.houseofbatteries.com/battery-chemistry-chart-i-52-l-en.html battery chemistries] generate different voltage potentials.  For example, NiMH rechargeable batteries create about 1.2 volts, alkaline disposable batteries create about 1.5 volts, lead-acid rechargeable batteries create about 2 volts, and lithium batteries create 3-3.7 volts.  You can connect batteries in sequence to increase the difference in charge (voltage) between the battery terminal at the start of the sequence and the battery terminal at the end; this is called placing the batteries in ''series''.  By placing 6 lead-acid cells in series you can make a 12V battery (which is what we use for robots).  When you buy a 12v SLA battery, it really contains 6 individual 2V cells in one package.  The lead-acid battery is the oldest type of battery, and is the one we still use on our robots, lead-acid batteries have lead terminals and sulphuric acid electrolyte.  
 
+== Multimeter ==
 You can use a meter called a voltmeter or a [multimeter to measure the amount of voltage "pressure" a battery exerts.  Multimeters are inexpensive ($5-25) and incredibly useful; every house should have at least one.  To learn how to use a multimeter, see [https://learn.sparkfun.com/tutorials/how-to-use-a-multimeter this tutorial]