Guess.
Make sure they are all off first and turn them on one by one until you notice one that doesn't do any thing to your surroundings.
When switches or any circuit opening devices are in series with each other, they all have to be in the closed position to energize the load.When switches or any circuit opening devices are in parallel with each other, any one of the switches or circuit opening devices in the closed position will energize the load.
A switches main purposes is to stop the current flow in a closed circuit.
Circuit
Switches control the flow of electric current in a circuit. In an open circuit, the switch is off, interrupting the flow of current. When the switch is closed in a closed circuit, it allows the current to flow continuously through the circuit.
A switch in a circuit controls the flow of electricity by opening or closing the circuit. When the switch is closed, it allows electricity to flow through the circuit, and when it is open, it stops the flow of electricity. Switches are commonly used to turn devices on and off.
In order for the load to be energized in a circuit with multiple switches in series, all the switches must be closed or in the "on" position. This is because switches in series function like an "AND" gate in digital logic, requiring all inputs to be true for the output to be true. If any one of the switches is open or in the "off" position, the circuit will be open and the load will not receive power. Therefore, all switches must be closed to complete the circuit and energize the load.
it's bulb 3
An AND GATE has two inputs that must both be true for the output to be true. If you have two switches in series then they must both be closed for current to flow. This is analogous to having two true signals on the input of an AND GATE.
The store is closed
An OR gate can be represented using two parallel switches because both switches can independently allow current to flow when either is closed. In this configuration, if either switch is closed (representing a logical "1"), the circuit is completed, resulting in an output of "1" from the OR gate. If both switches are open, no current flows, yielding an output of "0." Thus, the parallel arrangement effectively mimics the behavior of an OR gate.
POTS or PSTN
It refers to asystem whereby the loop of control is closed to outside interference.