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!Parallel
!Parallel
|----
|----
|V<sub>T</sub>=V<sub>1</sub>+V<sub>2</sub>+
|V<sub>T</sub>=V<sub>1</sub> V<sub>2</sub> …
|V stays same
|V stays same
|----
|----
|I stays same
|I stays same
|I<sub>T</sub>=I<sub>1</sub>+I<sub>2</sub>+
|I<sub>T</sub>=I<sub>1</sub> I<sub>2</sub> …
|----
|----
|R<sub>T</sub>=R<sub>1</sub>+R<sub>2</sub>+
|R<sub>T</sub>=R<sub>1</sub> R<sub>2</sub> …
|1/R<sub>T</sub>=(1/R<sub>1</sub>)+(1/R<sub>2</sub>)+
|1/R<sub>T</sub>=(1/R<sub>1</sub>) (1/R<sub>2</sub>) …
|----
|----
|}
|}

Revision as of 02:13, 11 April 2007

Some basic definitions, equations and analogies of electricity.

Definitions

Symbol Unit Description Water Analog Elec. Units Base Units
Voltage V volt (V) Pressure (Potential) difference due to charge difference Head: Pressure (Potential) difference due to height difference J/C kg•m²/(s³•A)
Current I amp (A) Flow of charge in charge/time or colombs/sec Flow: Flow of water in volume per time such as liters/sec C/s or W/V A
Resistance R ohm (Ω) Opposition to the flow of charge Friction: Opposition to the flow of water V/A kg•m²/(s³•A²)
Power P watt (W) Energy/Time = Power=Current*Voltage Power: Power=Current*Pressure J/s or A•V kg•m²/s³
Energy E watthour (Wh) The ability to do work Energy: The ability to do work 3600 J kg•m²/s²

Equations

P=IV
Power=Current*Voltage
look familiar see P=Q*H*e/k
V=IR
Volts=Current*Resistance
I=V/R might be more edifying since current is usually the result of pressure acting on resistance.
This only applies to ohmic circuits, those circuits which display a linear relationship between current and voltage (i.e. the resistance does not change based upon current or voltage).
Series Parallel
VT=V1 V2 V stays same
I stays same IT=I1 I2
RT=R1 R2 1/RT=(1/R1) (1/R2) …

Analogies

The following animated analogy has much information to go along with it. This analogy is a combination of many analogies, and although has the problems endemic to all models, I feel that it is quite good. Please leave feedback, questions and lambastings on the discussion tab above. Look for an update in February 2007.

Water Tank - Electricity Analogy
Component Analog
Tank Battery
Tank Vertical Difference Battery Voltage Difference
Water Flow Electrical Current
Mechanical Energy Appliance (Blender) Electrical Energy Appliance
Power=Head*Flow Power=Voltage*Current

For each example, ask yourself:

  • How fast will the battery run out?
  • How fast will the virgin margaritas be made?
  • And most importantly why?

If you would like to do math to support these analogies, use:

  • Feet = volts
  • GPM = amps
  • Each blender has a resistance of 6 Feet/GPM = 6 ohms

1 Tank 1 Blender

Series 1T1B.gif

  • This is the test case (datum).

1 Tank 2 Series Blenders

Series 1T2B.gif

Notice that:

  • The flow is 1/2 the speed of our test case.
  • The two blenders in series are each going 1/4th the speed of our test case.

1 Tank 2 Parallel Blenders

Parallel 1T2B.gif

Notice that:

  • Each blender is at the same speed as our test case.
  • The flow from the tank is twice as fast as our test case.

2 Parallel Tanks 1 Blender

Parallel 2T1B.gif

Notice that:

  • The blender is the same speed as our test case.
  • The flow from each tank is half as fast as our test case.

2 Series Tanks 1 Blender

Series 2T1B.gif

Notice that:

  • The blender is 4 times the speed as our test case.
  • The total flow is twice the speed as our test case.

Links

http://www.uuhome.de/william.darden/
Everything you every wanted to know about Lead Acid batteries.
Car and Deep Cycle Battery FAQ
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/dccircon.html#c1
Fantastic site on physics in general. Easy to understand, but accurate information on DC Circuits.
HyperPhysics - DC Circuits
http://library.thinkquest.org/10796/ch11/ch11.htm
Some easy to follow basic theory.
Lesson 3: Electricity - Colegio Franklin Delano Roosevelt
http://science.howstuffworks.com/electricity.htm
Some more information on electricity. Not wrot with error like at least one of their other pages.
How Stuff Works - Electricity
http://cnx.org/content/m1000/latest/
Understanding current

See Also

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