When both switches are connected to the same terminal then it completes the circuit and turns the light on. When the switch is on current flows along the black wire through the switch to the light and then returns to ground through the white wire to complete the circuit.

Etekcity Smart Wifi 3 Way Light Switch Eswl03 Vesync
How does a 3 way light switch work. If one set of lanes is closed a crossover in the median moves traffic over to one of the lanes normally used for traffic going in the other direction. In this diagram power enters the fixture box. In my mind i like to think of three way switches as like a construction zone on a four lane highway. This is known as the common screw and its usually black instead of brass or silver. The switch simply opens off or closes on the connection between the two terminals on the switch. Red and blue wires link traveler terminals of both switches.
Another dead giveaway of a three way switch is the absence of on and off markings. In this article we will solve the mystery of three way switches. 3 way switch a 3 way switch has 3 terminals. Whenever you flip either one of the switches the light changes its state if it is on it turns off and if it is off it turns on. A three way light switch is different than a traditional single pole light switch as it contains an extra screw to connect an extra wire. If there were no second crossover traffic would stop.
In a hallway or large room for example installing three way switches at both ends lets you turn the light fixture on or off from both locations. 2 brass terminals for the 2 traveler wires and 1 common black terminal for the common wire. The black hot wire connects to the far right switchs common terminal. The switch can connect to either terminal. A three way wall switch is a common type of light switch that makes it possible to control a ceiling light or other electrical fixture from two different locations in a room. For example they can be arranged so that the feed cable runs to the first three way switch then to the light fixture box then to the second three way switch.
This 3 way light switch wiring diagram shows how to do the light switch wiring and the light when the power is coming to the light fixture. If you have ever wondered how this arrangement works and how each switch knows what the other switch is doing then read on. A three way light switch allows one light to have two different light switches often in two different rooms for convenience. In this video we look at how light switches work in this video we look at a simple one gang one way switch as well as a one gang two way switch as well as an intermediate switch. Three way switches can be wired in a number of different ways depending on where they are located relative to the light fixture in the circuit cable runs. A 3 way switch circuit is always comprised of two 3 way switches that control light s or device s from two different locations.
The three way switch has three terminals inside it instead of two.