DIRECT CURRENT CIRCUITS
Rtot = Σi Ri
(1/Rtot) = Σi (1/Ri)
 |
Gustav Kirchhoff (1824 - 1887) |
Rule 1: The currents entering any junction
equal the currents leaving that junction. (Conservation of
charge!)
Rule 2: Around any loop, the potential
rises equal the potential drops. (Conservation of energy!)
Typical
Example for Application of Kirchhoff Rules...
A collection of successively more elaborate worked
examples.
Charging, q(t) = Q[1 - e(-t/RC)];
Discharging, q(t) = Qe(-t/RC).
Simple RC circuit!
FACTS ABOUT SHOCKS
1-10 Milliamperes--- Person
will feel little or no electrical shock effects or sensation.
10-20 Milliamperes--- Painful shock will occur like a jolt,
but muscle control will not be lost at this amperage.
20-75 Milliamperes--- This shock is more serious. You'll
receive a a painful jolt and muscle control will be lost resulting
in the inability to let go of something you may have grabbed that
is shocking you.
75-100 Milliamperes--- As the current approaches 100
milliamperes, ventricular fibrillation of the heart occurs and
damage is done.
100-200 Milliamperes--- Ventricular fibrillation occurs and
death can occur if medical attention is not administered
quickly.
Over 200 Milliamperes--- Severe burns and severe muscle
contractions occur. Your heart can stop during a shock because the
chest muscles put pressure on the heart. Internal organs can be
damaged at this stage and if you survive, a painful recovery can
be expected. What may surprise you about this level of shock is
that through this clamping effect on the heart, ventricular
fibrillation is avoided and the chances of a person's survival are
good if the victim is promptly removed from the electrical
circuit.
Current or Voltage?
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