##
__ __* 1 Law *

*1 Law*

**"The current in a circuit is directly proportional* to the applied voltage**

**and inversely proportional** to the**

**circuit resistance."**Ohm's Law is expressed by the equation

**I = E / R**

Spoken as, "

**Amps**is equal to volts divided by

**resistance**."

So... what does directly and inversely proportional mean?

*** Directly Proportional...**...means that when one quantity increases▲ the other increases▲,

*when one decreases ▼the other decreases ▼*

**or**

**** Inversely Proportional,**...means that when one quantity increases▲ the other decreases▼

*when one decreases ▼the other increases ▲*

**or**So, when we say Ohm's Law,

**"The current in a circuit is directly proportional* to the applied voltage**

**and inversely proportional** to the**

**circuit resistance."**We are saying that as the circuit's

**current**goes up ▲

**the applied**

**voltage**is also going up ▲

and at the same time that the circuit's

**current**is going up ▲the circuit's

**resistance**is going down ▼

The

**current**and

**voltage**rise and fall at the same time because they are

*...*

**Directly Proportional**they both go up at the same time ▲▲ or they both go down at the same time ▼▼

The

**current**and

**resistance**rise and fall in opposite directions because they are

**Inversely***...*

**Proportional**As one goes up ▲the other goes down▼at the same time ▲▼.

Does that make sense?

OK so... if the circuit's

**current**is decreasing ▼, what is the circuit's

**voltage**doing?

How about the circuit's

**resistance**? What is it doing when the circuit's

**current**is decreasing ▼?

The answer is that the circuit's

**voltage**is going down ▼when the

**current**is going down ▼because they are

*▼▼*

**Directly Proportional***and the circuit's*

**resistance**is going up ▲when the

**current**is going down ▼ because they are

**Inversely***.. ▼▲.*

**Proportional**One more time,

**"The current in a circuit is directly proportional* to the applied voltage**

**and inversely proportional** to the**

**circuit resistance."**The

**current**

**(called**

**amps**represented by the letter

**I**in a circuit)

is directly proportional ▲▲or ▼▼ to the applied

**voltage**(represented by the letter

**E**

**...**

*and*the

**current**is also inversely proportional ▲▼or ▼▲ to the circuit

**resistance**(represented by the letter

**R**)

Expressed as,

**I = E / R**

*Another way to express Ohm's Law is with triangle charts >*

*4 triangle charts*

##
__ 4 Quantities P-I-E-R __

__4 Quantities P-I-E-R__P or Watts is not considered a part of "Ohm's Law" but is commonly referenced in Ohm's Law calculations.

The term "watts" originated in Watt's law which is defined as,

##

This equation;

Formula 1)

Formula 2)

Formula 3)

This equation;

Formula 4)

Formula 5)

Formula 6)

This equation;

Formula 7)

Formula 8)

Formula 9)

This equation;

Formula 10)

Formula 11)

Formula 12)

If you know the value of any 2 quantities, you can find the third by using one of the above 12 formulas.

Example;

You want to find the watts (P) and you already know the amperage (I) is 5 amps and the voltage (E) is 10 volts. Look through the "P" formulas above for the one that contains I and E. Use formula 7: P = I x E.

Now replace the letters with your values; P (watts) = 5 (amps) x 10 (volts) or P = 5 x 10.

Now solve for P; 5 x 10 = 50, P = 50 watts.

*

##

Missing, in the formulas, is temperature and it's effect on resistance.

As the temperature increases the resistance also increases.

It is as though you solved this equation; E = I x R finding 10 (E) volts = 5 (I) amps x 2 (R) ohms.

But then a change in temperature creates more resistance and when you are not looking it erases your 2 ohms and changes it to 3 ohms leaving you with an faulty calculation.

To electricians, the National Electrical Code addresses this flaw by adding temperature "correction factors" to the allowable conductor ampacity. 2017 NFPA 70 NEC 310-15.

The effect of rising temperatures increasing resistance is noticed during a summer heatwave.

As the summer air temperatures rise, it increases the resistance in the cross country, overhead power lines.

This added resistance is like a "heat monster" consuming electricity and wasting it with no purpose.

The additional electrical demand overloads the utility and sometimes creates an electrical blackout.

During an electrical blackout the news journalists will mention of the added electrical demand of air conditioners but many fail to note the added electrical demand of the "heat monster" .. that invisible electrical consumer that may have also been unseen by Professor Ohm.

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via GIPHY Air Resistance

###

More from this author; http://120v.blogspot.com/

Using facial muscles for resistance to electrical current;

Khan Academy Free online math lessons

http://www.khanacademy.org/math/arithmetic

Tony R. Kuphaldt A free series of textbooks on the subjects of electricity and electronics

**Electrical energy, expressed as "P" measured in watts***The Watt's Law formula,***P = I x E***is spoken as "watts (***P***) is equal to amps (***I***) times volts (***E***)"*

**P**represents power or electrical energy and is measured in wattage or**watts**identified by the letter W.**I**represents the intensity of electrical**current**and is measured in amperage or amps identified by the letter A.**E**represents electromotive force, EMF and is measured in**voltage**or volts identified by the letter V.**R**represents**resistance**and is measured in ohms identified by the omega symbol; Ω

##
* 12 formulas * *

This equation; *12 formulas **

**√***E = I x R = P / I =**(PxR)*represents the first 3 formulas;Formula 1)

**Volts (represented by the letter E) is equal to amps (letter I ) times resistance (R).***E = I x R*Formula 2)

**Volts is equal to watts (P) divided by amps.***E = P / I*Formula 3)

**√***E =**(PxR)***Volts is equal to the square root of the answer to watts times resistance.**This equation;

**√***I = E / R = P / E =**(P/R)***represents;**Formula 4)

**Amps is equal to volts divided by resistance.***I = E / R*Formula 5)

**Amps is equal to watts divided by volts.***I = P / E*Formula 6)

**√***I =**(P/R)***Amps is equal to the square root of the answer to; watts divided by resistance.**This equation;

**P = I x E = E**^{2}**/ R = I**^{2}*represents;***x R**Formula 7)

*Watts is equal to amps times volts.***P = I x E**Formula 8)

**P =****E**^{2}*Watts is equal to volts squared divided by resistance.***/ R**Formula 9)

**P =****I**^{2}*Watts is equal to amps squared times resistance.***x R**This equation;

*R = E / I = P /***I**^{2 }*=***E**^{2}**represents;***/ P*Formula 10)

**Resistance is equal to volts divided by amps.***R = E / I*Formula 11)

*R = P /***I**^{2}**Resistance is equal to watts divided by the answer to; amps squared.**Formula 12)

*R =***E**^{2}**Resistance is equal to volts squared divided by watts.***/ P*If you know the value of any 2 quantities, you can find the third by using one of the above 12 formulas.

Example;

You want to find the watts (P) and you already know the amperage (I) is 5 amps and the voltage (E) is 10 volts. Look through the "P" formulas above for the one that contains I and E. Use formula 7: P = I x E.

Now replace the letters with your values; P (watts) = 5 (amps) x 10 (volts) or P = 5 x 10.

Now solve for P; 5 x 10 = 50, P = 50 watts.

*

*Basic Electricity US Navy Dover Publications ISBN 0-486-20973-3 shown below*##
__ 1 Flaw __

Missing, in the formulas, is temperature and it's effect on resistance.

__1 Flaw__As the temperature increases the resistance also increases.

*Because temperature is not constant but constantly changing...**,,, the values calculated with Ohms law would also be changing.*It is as though you solved this equation; E = I x R finding 10 (E) volts = 5 (I) amps x 2 (R) ohms.

But then a change in temperature creates more resistance and when you are not looking it erases your 2 ohms and changes it to 3 ohms leaving you with an faulty calculation.

To electricians, the National Electrical Code addresses this flaw by adding temperature "correction factors" to the allowable conductor ampacity. 2017 NFPA 70 NEC 310-15.

The effect of rising temperatures increasing resistance is noticed during a summer heatwave.

As the summer air temperatures rise, it increases the resistance in the cross country, overhead power lines.

This added resistance is like a "heat monster" consuming electricity and wasting it with no purpose.

The additional electrical demand overloads the utility and sometimes creates an electrical blackout.

During an electrical blackout the news journalists will mention of the added electrical demand of air conditioners but many fail to note the added electrical demand of the "heat monster" .. that invisible electrical consumer that may have also been unseen by Professor Ohm.

����������������������������������������������������

via GIPHY Air Resistance

###
** Links **

**Links**Single Pole article |

Article on 3 way switch wiring methods (to read the article, click the photo) |

Nailing up boxes article |

Drilling walls for house wiring article |

Using facial muscles for resistance to electrical current;

Khan Academy Free online math lessons

http://www.khanacademy.org/math/arithmetic

Tony R. Kuphaldt A free series of textbooks on the subjects of electricity and electronics

http://www.ibiblio.org/kuphaldt/electricCircuits

*Basic Electricity US Navy Dover Publications ISBN 0-486-20973-3

http://www.grc.nasa.gov/WWW/K-12/airplane/ohms.html

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

http://phet.colorado.edu/en/simulation/ohms-law

http://www.kpsec.freeuk.com/ohmslaw.htm

http://www.ndt-ed.org/EducationResources/HighSchool/Electricity/ohmslaw.htm

http://www.teachersdomain.org/resource/hew06.sci.phys.maf.ohmslaw/

*Basic Electricity US Navy Dover Publications ISBN 0-486-20973-3

http://www.grc.nasa.gov/WWW/K-12/airplane/ohms.html

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

http://phet.colorado.edu/en/simulation/ohms-law

http://www.kpsec.freeuk.com/ohmslaw.htm

http://www.ndt-ed.org/EducationResources/HighSchool/Electricity/ohmslaw.htm

http://www.teachersdomain.org/resource/hew06.sci.phys.maf.ohmslaw/

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