(Volts = amps X resistance)
(A handy mnemonic:
Cover any letter to
see how it is calculated. ie. -Cover “R”
and you see “E / I” )
Direct current ( DC ) occurs when electrons flow in one direction continuously along a
conductor. This is the kind of current obtained from batteries and is generally safe to work
with at low voltages, and is the main kind of current we will be working with in the our
initial circuit constructions.
Alternating Current ( AC ) occurs when the direction or polarity of the electron flow
alternates direction. AC is better suited than DC for transmission through long distance power lines.
Household (wall plug) current in North America delivers 110-115 volts, alternating at 60 times a
second (60 Hz). A wire carrying AC will induce a current in a nearby wire.
Note: “Wall current” (110-115 VAC) is a dangerous, potentially life-threatening energy
source. Do not use it for work you are doing at MassArt without the advice
and oversight of faculty or staff who can assure your work is done safely.
Anyone who ignores this advisory will not be allowed to use the lab and will be
immediately dropped from the Electronic Projects class.