2002-03-06 I don't think most people have any concept of any of the electrical units. The concept of current, voltage, resistance, and power and their interrelations is foreign to most people. I'm sure most people associate the unit watt with light bulbs. The higher the wattage, the brighter the bulb. And with some heating elements. 1500 W is hotter than 1250 W. But to know that the power in watts is the product of the current in amps and the tension in volts is quite a different thing.
If most people did have a feeling for the electrical units, they would comprehend joules better than kilowatt hours. It would be easy to comprehend that a 100 W bulb converts electrical energy in the form of voltage and current into light and heat at a rate of 100 J/s. A 1500 W hair dryer converts the same energy into heat, some light (glowing coils) and moving air (the fan) at a rate of 1500 J/s. 15 times more than a 100 W light. Unless one knows the interrelation between voltage, current, resistance, power and energy, then the concept of energy in either watt hours or joules is lost. John ----- Original Message ----- From: "Joseph B. Reid" <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[EMAIL PROTECTED]> Sent: Wednesday, 2002-03-06 19:02 Subject: [USMA:18589] Re: Metrication and goal setting > Bill Hooper wrote in USMA 18506: > > >on 3/4/02 11:48 AM, Joseph B. Reid at [EMAIL PROTECTED] wrote: > > > >> Because ordinary people, as dintinct from physicists, think much more in > >> terms of hours and minutes rather than seconds. Electricity bills > >> recognize this by using the hour as their time unit. > > > >I don't believe "ordinary" people think in terms of hours and minutes when > >thinking of their electric bill. I think they think in terms of > >kilowatt-hours, but ONLY in the context that: > >(1) their bill tells them how much energy they used IN KILOWATT-HOURS, and > >(2) the price they pay is given IN CENTS PER KILOWATT-HOUR. > > > >They have no idea (most of them) how much a kilowatt-hours is, or what it > >has to do with "hours" at all. Many people will use the term "kilowatts" to > >describe their energy use in kilowatt-hours, simple dropping off the "hours" > >because they don't know what it signifies and don't think it makes any > >difference. > > > "Ordinary" people know what a kilowatt is. The consumptions of their > household devices in watts or kilowatts are posted on all of them. People > can more easily understand watts and hours than joules and seconds. The > trouble is that our conception of time is in hours, and there is an awkward > 3600 seconds in an hour; and the joule is not met in everyday life. > > > > > Joseph B.Reid > 17 Glebe Road West > Toronto M5P 1C8 TEL. 416-486-6071 >
