(i) Circuit diagram of one lamp controlled by two switches
From this circuit picture we can understand that one lamp control by two SPDT switch.Two switch are having a separate position. And its upper two points and lower two points are connected two a wire.Its hot terminal and neutral terminal are connected to a battery positive and negative socket respectively.From this circuit you control this bulb from different two locations.
(ii) Circuit diagram of one lamp controlled by three switches
From this picture i can understand that a lamp controlled by two 3-way and one 1-way switch. Here not applicable SPST switch because most of the heavy reason is it have only one pole. So we can’t used this switch.3-way and 4-way switches make it possible to control a light from multiple locations. Such as the top and bottom of a stairway, either end of a long hallway, or multiple door ways into a large room. These switches appear externally similar to (SPST) switches. But have extra connections which allow a circuit to be controlled from multiple locations. Toggling the switch disconnects one “traveler” terminal and connects the other.Electrically, a typical “three-way” switch is a single pole, double- throw (SPDT) switch. By correctly connecting two of these switches together. Toggling either switch changes the state of the load from off to on, or vice versa. The switches may be arranged so that they are in the same orientation for off, and contrasting orientations for on.