curvature noun [U or C]. âº the âstate of being âcurved or âbent: the curvature of the earth's âsurface a âpronounced curvature of the âspine. (Definition of curvature from the Cambridge Advanced Learnerâs Dictionary & Thesaurus Â© Cambridge University Press). See all translations.
The Apple Watch uses your age, gender, height and weight, in addition to the GPS in your iPhone and data from its own built-in sensors, to calculate both your resting calories and ones you burn during exercise.
How Apple Watch measures your heart rate. The heart rate sensor in Apple Watch uses what is known as photoplethysmography. This technology, while difficult to pronounce, is based on a very simple fact: Blood is red because it reflects red light and absorbs green light.