Electrical Engineering 1 – Basics
Resistors and Capacitors
To find the equivalent resistance of resistors in series you add them. If the resistors are in parallel the equivalent resistance is equal to the reciprocal of the sum of the individual resistances reciprocals. For capacitors the equations are the exact opposite.
Basic Prefixes:
tera T 10^12
giga G 10^9
mega M 10^6
kilo k 10^3
- – -
milli m 10^-3
micro u 10^-6
nano n 10^-9
pico p 10^-12
femto f 10^-15
Conversions:
1 electron = 1.6*10^-19 C
1 C = 6.25*10^18 electrons
1 V = (1 N * 1m)/(1 C)
1 A = 1C / 1s
Laws
When solving electrical circuits some basic laws should be known.
Ohm’s Law: V=IR
where V = voltage(V)(volts)
I = current(A)(amperes)
R = resistance(Ω)(ohms)
Resistor Color Codes
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Gray 8
White 9
Gold 5%
Silver 10%
- 20%
To read resistors the first 2 colors represent the ones and tenths place for a number and the third color represents the multiplier in powers of 10. The last band represents the tolerance percentage since no resistor is perfect.
Example) Blue Red Brown Silver
=62 * 10^2 = 6.2K Ω
Real Value : (.95)(6200)Ω < R < (1.05)(6200)Ω
Ideal Voltage and Current Sources
Ideal voltage sources supply a constant voltage with current that is dependent on the circuits equivalent resistance. An ideal current source supplies a constant current with a voltage that is dependent on the circuits equivalent resistance.
admin | 
July 26, 2010 2:12 pm
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