Resistance and Resistors

1
Resistance and Resistors
George Simon Ohm "Ohm's law" - the relationship
that the current through most materials is
directly proportional to the potential difference
applied across the material. RE/I
Resistance All objects which current flows
through impart a hindrance to the electron flow.
Measured in W (Ohms) The Formula symbol is R
2
Most objects can only handle a threshold amount
of current before they overload
Resistors a Device with a known value of
resistance. Used to control voltage and current.
Fixed Resistors Single value of
resistance Three common types Carbon-compositi
on Film Wire-wound
3
(No Transcript)
4
Carbon-composition Resistors A Powdered carbon
mixed with a glue-like binder. Which is inside a
protective Epoxy housing. (Most common type)
Film Resistor High temp resistor which is made
of a ceramic element that has a film of either
carbon or metallic compound.

Wire-Wound Resistor Handles High heat A core
of ceramic is used and a resistance wire is wound
around it. Then it is coated with a ceramic or
enamel coating.
5
Power Rating The value that is assigned to a
resistor related To how much Wattage it can
dissipate. Usually corresponds with its physical
size. The larger the Resistor the higher its
wattage value.
6
Variable resistors Potentiometer or Rehostat
are able to change their values
Potentiometer Carbon film element Rehostat
Nickle-Chrome element wire
7
(No Transcript)