The correct option is (a) 1 only.
Explanation
The stethoscope is a medical instrument used for listening to internal sounds of an animal or human body. Its functioning is based on the physical principles governing the propagation of sound waves through a confined medium, specifically utilizing the laws of reflection.
Statement-wise Analysis:
- Statement 1 is Correct: The sound of the patient's heartbeat reaches the doctor's ears by multiple reflection. When sound enters the tube of the stethoscope, it undergoes repeated reflections against the inner walls of the tube. This process guides the sound waves from the chest piece to the earpieces, preventing them from spreading out and ensuring that the sound intensity is maintained.
- Statement 2 is Incorrect: The tube is designed to reflect sound, not absorb it. If the material or structure of the tube absorbed the sound energy, the signal reaching the doctor's ears would be too weak to be useful. The inner surface is smooth to facilitate efficient reflection, ensuring the sound travels through the tube with minimal loss of energy.
Key Takeaway:
Stethoscopes function on the principle of multiple reflection of sound, which allows sound waves to travel through a tube over a distance without significant loss of amplitude.