No but I think you might be confusing two different sets of equations....
1) If you have a fixed value resistor then the current flowing in the resistor is given by the equation: I = V/R Notice that if you double the voltage V you get double the current I.
2) The power (Watts) consumed by a piece of electric equipment is given by the equation W = I x V. Lets say you were designing two different toasters - one designed to work on 240V and one designed to work on 120V. You wouldn't want the one running on 120V to take twice as long would you? So you design them both to use the same amount of power. If one operates on half the voltage it needs twice the current to produce the same power. eg V x I = (V/2) x (Ix2)
Look at it another way. A fridge needs to burn a ceratain amount of power to keep the contents cold. If you feed the fridge twice the voltage it only needs half the current to keep the power the same.
In article , snipped-for-privacy@fastmail.fm mentioned...
If a light is 120W for example, the light will take 1A at 120VAC or .5A at 240VAC. It's the power that stays the same as the voltage changes. So the resistance for the 240VAC light is four times the resistance of a 120VAC light.
Understand, rubber band?
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My email address is whitelisted. *All* email sent to it goes directly to the trash unless you add NOSPAM in the Subject: line with other stuff. alondra101 hotmail.com Don't be ripped off by the big book dealers. Go to the URL that will give you a choice and save you money(up to half).
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You'll be glad you did! Just when you thought you had all this figured out, the gov't changed it:
In article , snipped-for-privacy@pandoraBOX.be mentioned... [snip]
Kind of a sorry example. The fridge could run at four times the power, but for one fourth the time, since it's a duty cycle type of appliance.
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You'll be glad you did! Just when you thought you had all this figured out, the gov't changed it:
Actually if you apply 240 volts to a 120 volt lamp the current will double for a short time till the lamp disintergrates. What you tried to say, but not very clearly, was that a 240 volt lamp designed to produce 120 watts will take 1/2 the current a 120 volt lamp will use to produce 120 watts. Very simple questions sometimes require very carefull answers because the questioner does not have a good understanding of the subject or he would not be asking the question.
But equipment designed to operate on 120 and 240v has a switch (usually manual, sometimes automatic) that changes the "equivalent load" of the equipment so that it draws the equivalent amount of POWER.
A given load requires half the current at 240v as it does at 120v.
I = P/E
A 120 *WATT* load would draw 1 amp at 120 volts, but only 1/2 amp at 240 volts.
But if you want an argument.... I'm sure fridge pumps must have an optimum operating duty cycle at which the fridge overall is most efficient. In which case the fridge should be redesigned to operate close to that point regardless of the voltage that it's designed to run on.
I note you didn't propose a better example?
A toaster perhaps? Who wants to wait 4 times longer for their toast?
In article , snipped-for-privacy@pandoraBOX.be mentioned...
Or Pop Tarts. :o)
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My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
Well, the current of a light bulb doesn't obey the straight line V-I characteristic of a resistor. But yeah, the 120V light would definitely burn out at 240VAC.
Mea culpa.
Zackly.
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###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
In article , snipped-for-privacy@ARRL.NET mentioned...
Pure resistance? What's that mean? I thinkk you mean the resistance of the light is non-linear.
Pure? As opposed to unpure? Maybe you need to filter the light to make sure it's pure.. ;-)
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###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
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