V = Volts
R = Resistance (ohms, )
I = Current ( Amps)
Formular
Example
V
= R * I
5
* 2A = 10Vs
I
= V / R
10V
/ 5
= 2A
R
= V / I
10V
/ 2A = 5
Watts
W
= Watts
V = Volts
I = Current ( Amps)
Formular
Example
W
= V * I
10V
* 2A = 20W
I
= W / V
20W
/ 10V = 2A
V
= W / I
20W
/ 2A = 10V
W
= R * I2
5
* 22 = 20W
W
= V2 / R
10V2
/ 5
= 20W
R
= W / I2
20W
/ 2A2 = 5
R
= V2 / W
10V2
/ 20W = 5
AC Theory
RMS
0.707
Peak voltage
Impedance
AC current in a capacitive or inductive component.
Impedance is the resistance ( measured in ohms ) of a reactive component
( capacitor, inductor ) at a certain AC frequency.
Capacitor
Inductor
Xc
= 1 / ( 2 * Pi * f * C )
Xl
= 2 * Pi * f * L
where
Pi
= 3.14
where
Pi
= 3/14
f
= frequency in Hz
f
= frequency in Hz
C
= capacitance in Farads
L
= Inductance in Henry
eg
A
100uF cap at 50Hz
eg
A
20mH inductor at 50Hz
Xc
= 1/(2*3.15*50Hx*0.0001F)
Xl=2*3.14*50Hx*0.02
Xc
= 31.8 ohms
Xl
= 6.28 ohms
Multipliers.
Pica
0.000,000,000,001
1^-12
Nano
0.000,000,001
1^-9
Micro
0.000,001
1^-6
Milli
0.001
1^-3
Centi
0.01
1^-2
Unit
1
1
Kilo
1,000
1^3
Mega
1,000,000
1^6
Giga
1,000,000,000
1^9
Tera
1,000,000,000,000
1^12
The Metric system.
All measurements are based on a unit, and a multiplier,
like those above. ie for distance we use a measure called the meter,
and thats the only unit of distance we need to remember. We also
use a multiplier, so we call 1000 meters a KiloMeter, or 1/1000
of a meter is a MilliMeter. Easy.
Another easy one to remember is Centigrade as a
measurement of temperature. Water freezes at 0 degrees, and boils
at 100 degrees. Body temperature is about 32 degrees C.
)
