Incandescent lamps are nearly pure resistive loads with a power factor of 1. This means the actual power consumed (in watts) and the apparent power (in volt-amperes) are equal. Incandescent light bulbs are usually marketed according to the electrical power consumed. This is measured in watts and depends mainly on the resistance of the filament, which in turn depends mainly on the filament's length, thickness, and material. For two bulbs of the same voltage, type, color, and clarity, the higher-powered bulb gives more light. COUNT 5
QSN1 What does a power factor of 1 mean? ANS1 the actual power consumed (in watts) and the apparent power (in volt-amperes) are equal QSN2 What principally determines the wattage of an incandescent bulb? ANS2 the resistance of the filament QSN3 What determines the resistance of the filament? ANS3 the filament's length, thickness, and material QSN4 How close do incandescent lamps come to pure resistive loads? ANS4 Incandescent lamps are nearly pure resistive loads QSN5 All other things being equal, how does wattage affect light emitted? ANS5 the higher-powered bulb gives more light