Question

Devices using the multiple reflections of the sound wave are -
1. Stethoscope
2. Ultrasound Cleaning Machine
3. Megaphones
4. Echocardiography

• A. 1 and 3 are correct
• B. 2 and 3 are correct
• C. Only 3 correct
• D. 3 and 4 correct

Answer 1

The correct option is A 1 and 3 are correct

Megaphone (or speaking-tube):
A megaphone is a horn shaped tube that is used to address a small gathering of people at places like tourist spots, fairs, market places and during demonstrations. One end of the megaphone tube is narrow and the other end is quite wide. When a person speaks into the narrow end of the megaphone tube, the sound waves produced by his voice are prevented from spreading out by successive reflections from the wider end of the megaphone tube. Due to this, the sound of the voice of the person can be heard over a longer distance.
Stethoscope:
It is a medical instrument used to detect and study sounds arising within organs such as the heart and the lungs prior to treatment. The stethoscope consists of a bell and diaphragm (receiving head), connected by a Y-joint and rubber tubing to the ear pieces.