Internet of Things (IoT) Practice Exam 2026 – Comprehensive Prep Resource

The accelerometer is the correct choice because it is specifically designed to measure changes in motion and orientation. In smartphones, the accelerometer tracks the acceleration forces acting on the device, which allows it to detect various types of movement, such as walking, running, or cycling. By analyzing the data from the accelerometer, health apps can monitor your physical activity levels, step count, and even calculate distances traveled.

While the gyroscope does contribute to motion sensing by measuring the rotation of the device, it mainly provides data on the orientation rather than directly monitoring physical activity. The magnetometer is used for detecting magnetic fields, which is useful for compass applications, but does not measure motion or activity levels. The proximity sensor detects when an object is close to the phone's screen, such as during a phone call when you hold the device to your ear, but it does not gather information on physical activity. Thus, the accelerometer is the sensor best suited for tracking movement and activity levels in health-focused applications.