What are "3 way lamps"?

Answer by  bl834 (1317)

It's a lamp that takes a special kind of bulb that has two different filaments, allowing the bulb to vary it's brightness to three different levels depending on how many clicks you turn the knob usually. One filament is a lower wattage, the second is a higher wattage, and the third option of course is both on together.

Answer by  MrHardware (369)

Three way lamps are light bulbs with 2 filaments and low, medium, and high settings. On low only one filament is lit the lower wattage one. On medium only one filament is lit the higher wattage one. On high both filaments are lit producing the most light.