The Time Use Institute
Grocery Shopping:
Who, Where and When
October, 2008
Who Does the Grocery Shopping, and When Do They Do It?
Jack Goodman
The Time Use Institute
October 2008
www.timeuseinstitute.org
[email protected]
On a typical day,
THE MAXIMUM POWER TRANSFER THEOREM
RTH
+

VTH
IL
+
VLL
SOURCE
RL
(LOAD)
V L2
PL = I L V L =
RL
RL
VL =
VTH
RTH + RL
RL
2
PL =
V
2 TH
( RTH + RL )
Every choice of RL gives a different power value. Which value of RL maximizes PL ?
Consider PL as a function
Conservation of Charge
A nonconducting material
Atomic Structure
In the early 20th century, a New Zealand scientist working in
England, Ernest Rutherford, and a Danish scientist, Niels Bohr,
developed a way of thinking about the structure of an atom that
LOOP ANALYSIS
Another technique to determine all currents and voltages in a circuit
FIRST determine all CURRENTS in a circuit
THEN use OHMS LAW to compute the VOLTAGES
There are situations where the number of equations required
by Node Analysis is signifi
FIRSTORDER TRANSIENT CIRCUITS
FIRST ORDER CIRCUIT
A circuit that contains a single energy storing element,
either a capacitor or an inductor.
IN CIRCUITS WITH INDUCTORS AND CAPACITORS,
VOLTAGES AND CURRENTS CANNOT CHANGE INSTANTANEOUSLY.
THE APPLICATION,
AC STEADYSTATE ANALYSIS
SINUSOIDS
Review basic facts about sinusoidal functions
SINUSOIDAL AND COMPLEX FORCING FUNCTIONS
Behavior of circuits with sinusoidal independent sources
and modeling of sinusoids in terms of complex exponentials
PHASORS
Represent