Conduction and Current Polarization vs. Conduction Batteries,
Current, Resistance Ohms Law and Examples Resistivity and Examples
Power and Examples
Slide 2
Materials can do 2 things: Store charge Initial alignment of
charge with applied voltage Charge proportional to voltage
Temporary short-range alignment Conduct charge Continuous flow of
charge with applied voltage Current proportional to voltage
Continuous long-range movement Electrical Properties of
Materials
Slide 3
Charge Storage vs Conduction Storage Q = CV Charge in Coulombs
Energy stored in Joules Conduction V= IR (I=GV G=1/R) Charge flow
in Coulombs/second (amps) Power created or expended in Watts
Slide 4
Batteries Battery Electrochemical Source of voltage Positive
and negative 1.5 volt, 3 volt, 9 volt, 12 volt Circuit symbol
Slide 5
Current Coulombs/second = amps I = Q / t Example 18-1 Requires
complete circuit Circuit diagram Positive vs. negative flow
Slide 6
Resistance Resist flow of current (regulate) Atomic scale
collisions dissipate energy Energy appears in other forms (heat,
light) Applications Characterize appliance behavior Heater
(collisions cause heat) Regulate current/voltage on circuit board
Resistors and color code
Slide 7
Resistance and Ohms Law Storage vs. Conduction Q = CV (storage)
I = GV (conduction) Current proportional to voltage Proportionality
is conductance Use inverse relation V = IR Resistance Units
volts/amps = ohms Ohms law If V proportional to I, ohmic Otherwise
non-ohmic Example 18-3
Slide 8
Ohms Law Examples
Slide 9
Slide 10
Resistivity vs. Resistance Property of material vs. property of
device Similar to dielectric constant vs. capacitance Becomes
resistance vs. resistivity We use reciprocals, resistance and
resistivity published for materials, like K. High poor conductor,
good conductor (similar to K for storage) StorageConduction
