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Electronics Design and Technology
Ohms’s Law
Describes the relationship between current, voltage, and resistance.
•
Current
is directly related to the voltage
•
Current
is inversely related to the resistance
V= IR
is the formulaic representation of Ohm’s Law
•
Voltage = Current x Resistance
•
Current = Voltage/ Resistance
•
Resistance = Voltage/ Current
Charge is a representation of the amount of electrons present in a material.
The symbol for Charge (in a formula) is
q
.
Charge is the measure in
Coulombs
(C)
One Coulomb of charge
is 6.28 x10
18
electrons
The
Resistance
of a wire is affected by four factors
LENGTH OF WIRE
MATERIAL OF WIRE
CROSSSECTIONAL AREA OF WIRE
TEMPERATURE OF WIRE
Resistance
is directly related to the length of the wire
Resistance
is inversely related to the area of a wire
The symbol for Resistance (in formula) is
R.
Resistance
is measured in
Ohms
(Ω)
Voltage
is “electric pressure”
Voltage results from the build up charge in a particular location
With voltage it is possible to have a large voltage without having a large
amount of Charge
The symbol for Voltage (in a formula) is
E or V
Voltage is measured in
Volts
(V)
Ground
is an area of zero electric pressure (0 V)
•
Ground
is an infinite acceptor and donor of electrons
•
In a circuit without ground, the negative terminal of the battery is assumed to
be ground
Current
is the movement of charge
•
Current describes the number of electrons that pass a point in a given
interval of time
The symbol for Current (in a formula) is
I
Current is measured in
Amps (A)
Essential Knowledge
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View Full DocumentElectronics Design and Technology
Materials are classified based upon how well they allow electrons to pass through them
Conductors
allow electrons to pass through them easily
Semiconductors
do not allow electrons to pass through easily
Insulators
do not
allow electrons to pass trough
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 Spring '11
 Lewis

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