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1

How did you measure perceived brightness? If you used the visible spectrum, the increasing temperature as the power goes up will shift more of the output into the visible. If you measure total output over the whole spectrum, the relationship should be linear. The increasing resistance of the bulb should not be a problem if you truly measure power in. It ...


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If you are looking at visual brightness, then you have to fold the wavelength dependent sensitivity of the human eye to the approximate black body spectrum of the filament into the calculation. At low power the filament will emit mostly infrared radiation, which is not visible. Even at the max. temperature of practical filaments the color temperature of the ...


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If the only load is the wire, such as a hot wire cutter, then supply voltage and wire resistance are all that matter, and both formulas are equivalent. But most of the time, wire size is chosen so that most of the voltage appears on the load. As an example, a toaster uses a power cord with wires which drop much less voltage than the heaters - if this were ...


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Actually, we don't know that "filament bulb has straight Volatage vs Current graph": "The actual resistance of the filament is temperature dependent. The cold resistance of tungsten-filament lamps is about 1/15 the hot-filament resistance when the lamp is operating. For example, a 100-watt, 120-volt lamp has a resistance of 144 ohms when lit, but the cold ...


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Since I understand that power = V x Current, the power for a bulb can not be a constant if its resistant is assumed a constant. A normal mathematical thinking can confirm that. If the voltage and current don't change, then the power is constant. The electricity supplied from the wall is at 115V (more or less). If the resistance of the bulb is 1322 ohms, ...


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The power rating given on lightbulbs always refers to the power at a specified operational voltage (which is always given together with the power or implied by the type of socket). The power at different voltages is not easily predictable as the resistance of the filament will vary strongly in dependence of temperature (which depends on the dissipated ...


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As stated, you cannot. First, a fan speed value in m/s is meaningless. Presumably you are talking either about the speed of the fan blades, probably at their tips, or you are talking about the air velocity produced by the operation of the fan. In the first case, you have left out the diameter of the blades and their aerodynamic efficiency. In the second ...


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in Pfan = K FanSpeed^3 , K is not only an units conversion factor. In this specific case, the units factor will be one in W s3/m3 = (kg·m2/s3)(s3/m3) = kg/m , since m/s and W are from the IS of units Edit : it is an answer to the first question that had been changed for a new one ...


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Energy is required to push something over a distance. In the case of the elevator, when it's not moving a brake can be engaged and the power removed and the elevator will sit just fine. That's because it doesn't take any energy to keep something still. But wait, if all I want to do is keep the helicopter still, then it doesn't require any energy? Sort of. ...


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It's a good question, and I would be inclined toward B or C. You are worried about blockage, but I view that as an issue of aerodynamics, like the difference between a lifting airfoil and a stalled airfoil. If you are not asking the air to follow sharp turns, so the flow doesn't separate, you should be good to go. If you do need to make the air follow ...



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