What technology is used by mobile devices to detect changes in orientation, such as when the user rotates the device?

The correct answer is the accelerometer. An accelerometer is a sensor that measures the acceleration forces acting on a device, which allows it to detect changes in orientation and movement. When a user rotates a mobile device, the accelerometer senses the change in position relative to the direction of gravity and can determine the tilt or angle of the device. This information is often used to adjust the screen orientation automatically from portrait to landscape mode, enhancing user experience.

While the gyroscope, magnetometer, and proximity sensor have their own specific functions, they do not primarily serve the purpose of detecting orientation changes in the way an accelerometer does. The gyroscope also provides data on rotation and orientation, but it mainly measures angular velocity rather than straight acceleration due to gravity. The magnetometer senses magnetic field strength and direction, being more useful for compass applications. The proximity sensor detects the presence of nearby objects (typically to turn off the display during a call when the device is near the user’s face) and does not relate to orientation changes.