Answer: (A) Magnetic grid
Question Answer Analysis:
A rotary detection device is a device used to detect the rotation of an object and usually includes a sensor and a circuit.
These devices can be used in a variety of applications, such as measuring rotational speed, direction and steering. Common rotation detection devices include:
1. Photoelectric encoder: detect rotation by detecting the occlusion of the beam.
2. Resolver: detects rotation by detecting the movement of the magnet.
3. Hall-effect sensor: detects rotation by detecting changes in the magnetic field.
4. Mechanical switch: detect rotation by detecting the movement of mechanical parts.
5. Other types: including magnetoresistive sensors, capacitive sensors, etc.
These rotary detection devices can be selected in different types and sizes to suit a variety of different application scenarios.