How are reed switch sensors actuated?
The correct answer and explanation is :
Reed switch sensors are actuated by the presence of a magnetic field. These sensors are composed of two ferromagnetic contacts enclosed in a sealed glass tube. The contacts are normally open when the reed switch is in its unactivated state, but they close when a magnetic field is applied nearby.
The basic working principle is based on the magnetic field’s influence on the reed contacts inside the glass tube. The reed switch is typically made of thin metal reeds (usually nickel-iron) that are magnetized to be responsive to external magnetic fields. When a magnet (or magnetic field) is brought close to the reed switch, the reeds move due to the magnetic force. The movement of the reeds causes them to make contact with each other, closing the circuit. This closure of the circuit can then be used to trigger a response in the connected system, such as turning on a light, triggering an alarm, or activating other electronic components.
In most reed switches, the contacts inside the glass tube are normally open, meaning no current can flow through them unless the switch is actuated by a magnet. When the magnetic field is removed, the reeds return to their original position, and the switch reverts to its open state.
The actuation of reed switch sensors is highly reliable and can be used in various applications, including security systems, position sensing, and proximity detection. These sensors are often used in door/window contact sensors for burglar alarms, where the reed switch is placed on a door or window frame, and a magnet is placed on the door or window. When the door or window opens, the magnet moves away from the reed switch, causing it to activate.