Changes between Version 13 and Version 14 of ElectricalIntroduction

Timestamp:

Aug 21, 2017, 11:26:23 AM (8 years ago)

Author:

David Albert

Comment:

--

ElectricalIntroduction

@@ -25 +25 @@
 
 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.  
+
+When you get a static shock, you are often feeling thousands of volts! [[Image(static_shock.jpg, left)]]
+If you're feeling brave, try tasting the terminals of a 9v battery to see how 9v feels (this is not dangerous)
 
 == Multimeter ==
@@ -77 +80 @@
  The multimeter measures the number of electrons flowing through it.
 
+== Electromagnets ==
+
+== DC Motors ==
+
 * Exercise: use a multimeter to measure the current flowing through a DC motor
     * Unplug the bulb from the circuit above
@@ -128 +135 @@
 
 * What happened: all substances present some resistance to the flow of electrons; graphite presents a moderate level of resistance.  The more graphite the electrons must pass through, the higher the resistance.
+
+* Exercise: measure the resistance of other things (e.g. your fingers).  Try it with your fingers moist and dry and observe the difference.