Question

state the working principal of sethoscope and megaphone

Answer 1

The doctor puts the Ear piece ofstethoscope into his ears and places the lung piece above the surface of patient's body. The sound of heart beat reaches by undergoing multiple reflection of sound waves inside tube. The working of Megaphone and bulb horn is also based on multiple reflection of sound wave.

Answer 2

Essentially, megaphones and stethoscopes increase the volume of a sound, thus increasing its audibility. They both work on similar lines as the fundamental principal behind their working is the amplification of sound.

In a stethoscope the goal is to amplify the sounds produced when the valves of the heart close. (in some cases, the expansion and contraction of the arterial walls - the pulse is) This is achieved by using a diaphragm (the end with a flat, circular base that is placed on a patient) which resonates with the produced sound. This increases the amplitude and intensity of the sound that travels through a pipe and eventually reaches the doctor's ears.

A megaphone is used to broadcast a person's voice (usually to an audience). A (non-electric) megaphone focuses the sound waves from the source to a defined point, owing to its funnel-like shape. From the POV of a listener, the sounds seem louder when a megaphone is used because more sound waves are focused towards the listener. When this device is not used, sound waves are generally propagated all around and are dispersed in a multitude of directions. Thus, its intensity is diminished