What is another name for the reed switch?

• A. Magnetic switch.
• B. Thermal switch.
• C. Proximity switch.
• D. Pressure switch.

Answer: (A)

Reed switches operate when a magnetic field is present, so they are best described as magnetic switches. Inside a reed switch is a tiny pair of ferrous reeds in a glass envelope; when a magnet comes near, the reeds are drawn together, closing the circuit, and when the magnet moves away they separate, opening the circuit. This magnetic-activation characteristic is what sets them apart from other types: thermal switches respond to temperature, pressure switches respond to pressure, and proximity switches sense distance or presence using non-magnetic sensing methods. In alarm systems, that magnetic-field activation is why reed switches are commonly used in door and window sensors.