<P> A 3 - way lamp, also known as a tri-light, is a lamp that uses a 3 - way light bulb to produce three levels of light in a low - medium - high configuration . A 3 - way lamp requires a 3 - way bulb and socket, and a 3 - way switch . Unlike an incandescent lamp controlled by a dimmer, each of the filaments operates at full voltage, so the color of the light does not change between the three steps of light available . Certain compact fluorescent lamp bulbs are designed to replace 3 - way incandescent bulbs, and have an extra contact and circuitry to bring about similar light level . In recent years, LED three way bulbs have become available as well . </P> <P> Lamp bulbs with dual (carbon) filaments were built as early as 1902 to allow adjustable lighting levels . Large lamps of 500 - watt rating were used for street lighting in France, which had a second filament at 200 watts to reduce lighting costs . In 1933 in the United States, Westinghouse announced a dual - filament lamp for commercial lighting and a smaller lamp for residential use . </P>

Can you put a regular light bulb in a 3 way