"GreyCloud" <> wrote in message
news:...
> Dave wrote:
>>
>>
>> "GreyCloud" <> wrote in message
>> news:...
>>> Gene E. Bloch wrote:
>>>> On Wed, 17 Mar 2010 16:12:29 -0700, Gene E. Bloch wrote:
>>>>
>>>>> On Wed, 17 Mar 2010 17:51:11 -0500, Char Jackson wrote:
>>>>>
>>>>>> On Wed, 17 Mar 2010 15:35:16 -0500, "Dave" <>
>>>>>> wrote:
>>>>>>
>>>>>>> I'm done with this conversation. It is not only off-topic, at this
>>>>>>> point, it is becoming very boring trying to ensure what I'm
>>>>>>> responding to is actually true or not something contrived or
>>>>>>> twisted. You need to trust me on this one, I do know the difference,
>>>>>>> but am done with this topic.
>>>>>>> Respectfully,
>>>>>>> Dave
>>>>>> This is the second time you've promised you were done with this
>>>>>> thread, but you haven't slowed down yet. Here's hoping your latest
>>>>>> promise sticks.
>>>>> He's been done with this thread for a long time, only he hasn't
>>>>> realized it
>>>>> :-)
>>>>>
>>>>> He seems to have substituted insults for understanding. I see no need
>>>>> to
>>>>> respond further to his anger.
>>>>
>>>> Just for fun, I looked up his URL. Here's a copy & paste from it:
>>>>
>>>> "Watt's law is an improper name used for the Basic Power Formula:
>>>>
>>>> P = V x I "
>>>>
>>>> Note the word 'improper'.
>>>>
>>>> He couldn't seem to figure out that since the proper Watt's Law refers
>>>> to
>>>> steam, it doesn't refer to electricity. Par for his course, ISTM.
>>>>
>>>> Because of a font problem I replaced the dot in the formula above with
>>>> an
>>>> x.
>>>>
>>>> Now I ramble a bit:
>>>> Useful random fact: 746 W = 1 HP. 'Watt' is the metric (SI) unit of
>>>> power,
>>>> equal to one Joule/sec, and of course it is not in any way restricted
>>>> to
>>>> electrical contexts.
>>>>
>>>
>>> I think he is referring to James Watt. There isn't any Watts law in
>>> respect to electrical systems.
>>
>> Actually, James Watt never performed any electrical experiments, but
>> there is a Watt's Law that is used in electrics and electronics.
>
> Of course we always have the P=IE equation that is explained in physics
> books. There are also plenty of explanations in the physics books on how
> it has been equated to James Watt. In this I can quote:
>
> "WORK, POWER, AND ENERGY ... Before we can discuss the next important part
> of this lesson, power in d-c circuits, it is important that you know the
> difference between work, power, energy.
>
> In a scientific sense, work is the overcoming of the opposition. A man
> does work when he lifts a crated television set from the warehouse
> platform into a truck or when he drags the crate along the platform. But
> the man does no work at all, in the scientific sense of the word, no
> matter how hard he pushes or pulls if he does not lift or move the crate.
> If the resistance offered by the crate to being moved is not overcome, no
> work is done.
>
> Work is measured by the product of a force times the distance through
> which the force moves. In a mechanical system, the most common unit of
> work is the foot-pound.
>
> In an electrical system, work is measured in watthours or kilowatt-hours.
> One kilowatthour of work in an electrical system equals approximately
> 2,660,000 ft-lb (foot-pounds) of work.
>
> The work done by a man carrying a 50-lb audio amplifier up a flight of
> stairs 12 ft high is 50 lb X 12 ft = 600 ft-lb. From the standpoint of
> work done, it makes no difference whether the man does the job in an hour
> or in a minute.
>
> But the amount of power required to do the job does depend on time. The
> amount of power required to do a job in one minute is 60 times the power
> required to do it in one hour. The term "power" includes the idea of time.
> Power is the speed, or rate, of doing work. Then,
>
>
> power = work or work = power X time
> ----
> time
>
> The popular unit for measuring power in mechanical systems is the
> horsepower. If a machine can do 33,000 ft-lb of work in one minute, its
> power is one horsepower.
>
> The practical units of power in electrical circuits are the watt and
> kilowatt. One kilowatt (abbreviated kw) equals 1000 watts. Horse-power and
> watts are related as follows:
>
> 1 hp = 746 watts
>
> 1 kw = 1.34 hp
>
> The work done in an electrical circuit, kilowatthours, equals the power in
> kilowatts times the number of hours. For example, if the power required to
> operate a motor is 2 kw and the motor operates for 7 hr, the work done is
> 2 X 7 = 14 kwhr (kilowatthours).
>
> Energy is the capacity to do work. For example, if a battery is able to do
> 1 kwhr of work before it must be recharged, the energy stored by the
> battery is 1 kwhr. The difference between work and energy is that work is
> what has been done by a device, while energy indicates the amount of work
> which a source of energy is able to do.
>
> There are many types of energy. A moving car, for example, has mechanical
> energy. A charged battery has chemical energy. A hot stove has heat
> energy.
>
> An important concept about energy is that, when work is done, the energy
> used to do the work is never used up; it is simply changed from one form
> to another.
>
> For example, suppose a charged battery causes current to flow in a
> circuit. Chemical energy of the battery has changed to electric energy in
> the circuit. Suppose the electric energy of the circuit causes a
> vacuum-tube filament to heat up; now the electric energy has changed to
> heat energy. When someone talks into a microphone and thus generates an
> input signal to an amplifier, the acoustic energy of the sound waves is
> changed into electric energy."
>
> From my old physics handout lab sheets back in 1965.
>
>> It is taken from James Watt since what we are measuring in this
>> electrical application is power. Since it is a measure of power (which
>> Law Watt did compile), it is directly related to a unit of energy called
>> a Joule and indirectly related to Horsepower. Neither of those terms are
>> used much in electrical analysis, but when or if you attend a program on
>> electronics you will learn how to apply these and cross-check between any
>> or all of them, or either get a bad grade or flunk out. All of these
>> units of measurement are standards in electricity and used constantly. It
>> has no bearing on steam and/or mechanical energy producing devices that
>> Watt did perform experiments on, other than it is related due to it being
>> a measure of a form of power, amount of electrons that move past a noted
>> point at a noted rate of flow for a noted period of time.
>> You don't have to take my word for any of this, search for Watt's Law and
>> you will see references that show this is a Law describing electrical
>> power. If you read long enough you will find all the information I've
>> posted here, which agrees with your assessment for the most part, and if
>> you don't read far enough you may come to the conclusion Watt's Law has
>> nothing to do with electrical and you would be mistaken.
>>
>> There is a connection tho that watts
>>> really refers to how much work is done, and in this sense heat is
>>> released due to the work.
>>
>> You are indirectly correct in this as heat is a byproduct of power, in
>> this case electrical, and has to be factored in whenever you move past
>> the simplistic parts of circuit analysis.
>>
>> I think that a good read in a physics book
>>> shows the connection. The above that you posted pretty much ties it all
>>> together. I know that resistors have power ratings given to them, such
>>> as 1/8W, 1/4W, 1/2W, etc. Exceed the power rating and watch some smoke.
>>
>> There's some fun in letting the smoke out. :-D
>
> The worst smelling component is the old selenium rectifier. Phew!
>
Enjoyed your dissertation, well put and spot on.
Dave
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