Apple have introduced a smart watch that will provide information about heart beat. These watches will track users heart beat reading with a sensor located on the backside of the watch.
There will be infrared light and green LEDs in the device. These lights will work together and give an accurate heart beat reading.
Blood is red because it reflects red light and absorbs green light. The watches use green LED lights paired with light sensitive photodiodes to detect the amount of blood flowing through users wrist at any given moment.
When users heart beats, the blood flow in their wrist and the green light absorption is greater. Between the beats, its absorption is less.
By flashing its LED lights hundreds of times per second, These watch can calculate the number of times the heart beats each minute users heart rate.
