state law which is involved in the function of sphygmomanometer and briefly describe how it works?

Answer 1

As the blood pressure measuring cuff is inflated it squeezes off the flow of blood in the arteries within the arm. When a stethoscope is placed over the arteries there is no sound. As the pressure in the cuff is observed and reduced, blood flows and the pulse of the heart is heard. The sound of the higher and lower blood pressures (systolic and diastolic) can be distinguished. Blood pressure is measured in millimeters of mercury (often read directly from a mercury manometer) and 120/80 is common in a healthy person.

Answer 2

How about Pascal's Law which goes something like this: Pressure in a closed fluid system is transmitted equally and undiminished in all directions.