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Author Topic: Cartoon: Volts, Amps, Resistance  (Read 3668 times)

John Roberts {JR}

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Re: Cartoon: Volts, Amps, Resistance
« Reply #10 on: November 25, 2012, 10:15:15 pm »

The amp is currently stuck, the volt is only potentially there, the ohm is resisting the urge to leave, and the watt is powerless to do anything about it.

The watt is the "heat" caused by friction between the amp and the resistance when the amp is pushed through by the voltage.

JR
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Paul Dershem

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Re: Cartoon: Volts, Amps, Resistance
« Reply #11 on: November 25, 2012, 10:35:49 pm »

The watt is the "heat" caused by friction between the amp and the resistance when the amp is pushed through by the voltage.

JR

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Dennis Wiggins

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Re: Cartoon: Volts, Amps, Resistance
« Reply #12 on: November 26, 2012, 07:53:55 am »

The watt is the "heat" caused by friction between the amp and the resistance when the amp is pushed through by the voltage.

JR

Mr. Ohm's feet will be held to the fire due to overheating which will result from his refusal to let go of the rope.

-Wigs
« Last Edit: November 26, 2012, 07:59:13 am by Dennis Wiggins »
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Mike Christy

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Re: Cartoon: Volts, Amps, Resistance
« Reply #13 on: November 26, 2012, 11:29:43 am »

How do Watts fit into this metaphor?

Watt needs to be shown as how far AMP has moved through the constriction. That's the only result of the work ( power expended) being done here.
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Mark Oakley

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Re: Cartoon: Volts, Amps, Resistance
« Reply #14 on: November 26, 2012, 02:00:38 pm »

I think of power through a cable as water through a hose:

Voltage is the "pressure" of the water (like a garden hose with a fine mist head on the end of it (Hi Voltage)versus just being open and the water dribbiling out(Low Voltage)).

Amperage is the size of the hose (think potential here: is the hose a straw or a 12" conduit? This has nothing to do with the actual amount of power being drawn through the hose).

Wattage is the actual amount of water. Obviously you can get more water through a bigger hose. A fire hose going full tilt would be like 400A, 600V. Sipping water through a straw would be more like .5A, 120V.

I would re-label the cartoon so that the pipe was the Amperage and the character getting the squeeze is the Wattage.

-Mark
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John Roberts {JR}

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Re: Cartoon: Volts, Amps, Resistance
« Reply #15 on: November 26, 2012, 02:54:53 pm »

I think of power through a cable as water through a hose:
Water is a very popular and well worn analog for electricity.
Quote
Voltage is the "pressure" of the water (like a garden hose with a fine mist head on the end of it (Hi Voltage)versus just being open and the water dribbiling out(Low Voltage)).
Yes, kind of... Water pressure is analogous to electrical potential... voltage is the pressure that pushes current through the wire. However your example of an open and closed hose nozzle are examples of how different impedance or resistance, and current capability react.

The hose is like a speaker wire, and the nozzle setting is like a high impedance or low impedance speaker load. With the nozzle almost completely closed off (think 600 ohm headphones ) current flow (water flow) is low, and the voltage (pressure) in the hose remains high. Alternately if the nozzle is wide open (2 ohm load), the flow (current) is much greater, with water pressure (voltage at the end of the wire) much lower.

   
Quote

Amperage is the size of the hose (think potential here: is the hose a straw or a 12" conduit? This has nothing to do with the actual amount of power being drawn through the hose).
Amperage is directly analogous to the amount of water flowing through the pipe. The size of the hose is more analogous to wire resistance. Heavy gauge wire is like large diameter pipe. Just like getting good current flow to speakers is improved by thicker wire, wider pipes will get more water flow to your shower from the same water pressure.
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Wattage is the actual amount of water. Obviously you can get more water through a bigger hose. A fire hose going full tilt would be like 400A, 600V. Sipping water through a straw would be more like .5A, 120V.
bzzt.. amount of water (flow) is current, amount of still water is like charge sitting in a capacitor.. big capacitor, holds more water, capacitor filled up has more potential pressure (voltage).

Power does not fall out of the water analogy very neatly. The work (and heat) associated with a water pump is similar to power because it is directly related to flow (current) and pressure (voltage) of that water being pumped. I.E. Low flow and/or low pressure is easier on the pump than both high flow and high pressure at the same time.   
Quote
I would re-label the cartoon so that the pipe was the Amperage and the character getting the squeeze is the Wattage.

-Mark

The cartoon is actually quite good as is.. pipe diameter is resistance so making the pipe smaller increases resistance and restricts flow. Current is the amount of flow, and voltage the pressure pushing the current. The real Mr. Ohm is not turning over in his grave.

Mr Watt may be harder to please.  Power is harder to describe with literal images since it is the product of two linear characteristics, so a nonlinear product.

JR


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Bob Leonard

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Re: Cartoon: Volts, Amps, Resistance
« Reply #16 on: November 27, 2012, 01:07:28 am »

I think that what's being shown is that amp is being pranked by his buddys because he has a fat ass.
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Ben Johnson

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Re: Cartoon: Volts, Amps, Resistance
« Reply #17 on: November 27, 2012, 01:09:40 pm »

Mr Watt may be harder to please.  Power is harder to describe with literal images since it is the product of two linear characteristics, so a nonlinear product.
JR

It's imperfect, but I've always liked the waterwheel (the type that powered 1800s grain mills) as an example of how you can get the same amount of work from different voltage and currents. If you have a trough dumping water onto a waterwheel you can get a certain amount of work done.  Let's say a 10' drop with 1 gallon/second does x work.  If the water fell 20 feet you could get more work done (to be specific, the wheel would probably spin faster.  Still, more work).
But if the water fell only 3 feet, there's not a lot of potential drop, right?  So less work could be done.  But If the wheel were 10' wide, the size of a small river, that 3 foot drop with 100 gallons/second could supply a lot of energy as well.  You just need to have a mill/machine capable of working with the power supplied.

And if 1 gallon falling 1 foot does x amount of work, then 1 gallon falling 2 feet does 2x work.  If the quantity is then doubled, with each gallon already doing 2x work, you now have 4x work.  The same for 3 gallons each dropping 3 feet doing 9x work, etc.

The place this fails is actually at ohms law.  You can adjust the potential drop (voltage) and current (volume) independently, unlike in a circuit.

Ben
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John Roberts {JR}

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Re: Cartoon: Volts, Amps, Resistance
« Reply #18 on: November 27, 2012, 01:17:48 pm »

The water mass x height is real potential energy, and not just an analog for electricity Of course we can use the water wheel to make electricity. :-)

JR.
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