Consider the following statements regarding the reflection of sound in a stethoscope: 1. The sound of the patient's heartbeat reaches the doctor's ears by multiple reflection. 2. The tube of the stethoscope absorbs the sound to prevent echoes. Which of the statements given above is/are correct?

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.

NCERT Class 9 Science — Chapter 5: Sound

mcqeasy

Consider the following statements regarding the reflection of sound in a stethoscope:

The sound of the patient's heartbeat reaches the doctor's ears by multiple reflection.
The tube of the stethoscope absorbs the sound to prevent echoes.

Which of the statements given above is/are correct?

Official previous-year question

Verified 1 Aug 2026.

Options

A1 only
B2 only
CBoth 1 and 2
DNeither 1 nor 2

Did you get this right?

Solution

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.

Your note

More from Chapter 5: Sound

Consider the following statements regarding the propagation of sound: 1. The disturbance created by a source travels through the medium to the listener. 2. Sound waves are characterized as non-mechanical waves. 3. A material medium is mandatory for the transmission of sound. Which of the statements given above are correct?

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With reference to the characteristics of a sound wave, consider the following statements: 1. The distance between two consecutive compressions is called the wavelength. 2. The time taken for one complete oscillation is called the frequency. 3. The SI unit of frequency is Hertz. Which of the statements given above are correct?

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Consider the following statements regarding Ultrasound: 1. It refers to sounds with frequencies higher than 20 kHz. 2. Ultrasound waves scatter immediately when they encounter obstacles. 3. Ultrasound is incapable of penetrating metal blocks to detect flaws. Which of the statements given above is/are correct?

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The cleaning action of an ultrasonic cleaner is primarily achieved through:

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With reference to medical applications of sound, consider the following statements: 1. Echocardiography uses ultrasonic waves to form an image of the heart. 2. Ultrasonography uses X-rays to detect stones in the gall bladder. 3. Ultrasound can be used to break kidney stones into fine grains. Which of the statements given above are correct?

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Keep practising Chapter 5: Sound

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The correct option is (a) 1 only.

Explanation

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.