Question

The stethoscope used by doctors works on the principle of
(A) Refraction of sound
(B) Reflection of sound
(C) Interference of sound
(D) Absorption of sound

Answer 1

Stethoscope is a medical instrument for listening to the action of someone's heart or breathing, typically having a small disc-shaped resonator that is placed against the chest, and two tubes connected to earpieces.

Complete step by step
A stethoscope can be used to listen to the sounds made by the heart, lungs or intestines, as well as blood flow in arteries and veins. In combination with a manual sphygmomanometer, it is commonly used when measuring blood pressure. It has an air filled tube with a diaphragm at its one end . When this diaphragm is placed on the chest of a patient , it vibrates due to faint sound coming from the chest , these vibrations are channelised through the air filled tube and amplified by multiple reflections by the inner walls of the tube , thus it is based on the principle of reflection .

Note:
The word stethoscope is derived from the two Greek words, stethos (chest) and scopus (examination). Apart from listening to the heart and chest sounds, it is also used to hear bowel sounds and blood flow noises in arteries and veins.