Currents are moving charges,
similar to velocity, only Coulombs / sec rather than m/s
1 Coulomb / sec = 1 Amp.
Current in a wire travels
as a wave (light), individual electrons don't move as much
Current travels at the speed
of light, but it may be lower depending on the wire used.
Q = It
Current kills
.001
A -> Can feel it
.01 A
-> Kinda Hurts
.1 A
-> DIE!!! -> sort of like a resonant frequency with brain and nervous
system
1 A ->
Burn but not necessarily die
10 A
-> Really burned
50-100
A -> Death Row Electric Chair -- Burned and fried to a crisp !
***** When ever
Mr. Williams starts the electricity unit, sit as far back as possible,
never raise your hand, and never trust him -----> You will die!!!!
***** Don't believe
him if he says it won't hurt, because it will
(From personal experience)
***** Never leave
your seat, especially when you hear screams from the class before you,
because they are not screaming from the joy of physics !!!
RESISTANCE:
R = r
L / A
W
= Ohm !
Light bulbs resist flow
of electricity (Resistor)
Ammeter-slight resistance
Voltmeter - high resistance
Current like traffic, resistor
causes traffic jam, like a toll booth, give up some of the energy at each
Series circuit -- current
always goes through same resistors, no choice - increases resistance
Rts=R1+R2+...+Rn
Parallel circuit -- Current
splits and comes back together, like opening another lane for the traffic,
bigger area for current to go through, decreases resistance.
1/Rtp=1/R1+1/R2+...+1/Rn
Short circuit -- when there is a path of least resistance that allows the current to go around the resistor, instead of going through it.
V=IR (Ohm's law)
Voltage (EMF) is the change in potential -- in vs. out -- pressure to push the current through, like toll money, have to give it all up before you get back to the battery.
EMF = Electro Motive Force = voltage of a battery ignoring internal resistance
High current -> lots of friction -> heat -> molecules move faster -> resistance increases
P= W/t = qV/t = IV = V2/R = I2R
