Consider the following statements regarding the nature of sound waves: 1. Sound waves in air are longitudinal waves. 2. In a longitudinal wave, particles move perpendicular to the direction of wave propagation. 3. Light waves are examples of longitudinal waves. Which of the statements given above is/are correct?

Correct Option The correct option is (a). Explanation Waves are disturbances that transport energy. Based on the direction of particle oscillation relative to the direction of wave propagation, mechanical waves are classified into longitudinal and transverse waves. Statement-wise Analysis - Statement 1 is Correct: Sound waves in air are longitudinal waves. They propagate through the medium as a series of compressions (high pressure) and rarefactions (low pressure). - Statement 2 is Incorrect: In a longitudinal wave, the particles of the medium oscillate parallel to the direction of wave propagation. It is in transverse waves that particles oscillate perpendicular to the direction of propagation. - Statement 3 is Incorrect: Light waves are electromagnetic waves and are transverse in nature. In light waves, the electric and magnetic fields oscillate perpendicular to the direction of the wave's travel. Key Takeaway: Sound waves in fluids are longitudinal (parallel oscillation), whereas light waves are transverse (perpendicular oscillation).

NCERT Class 9 Science — Chapter 5: Sound

mcqmedium

Consider the following statements regarding the nature of sound waves:

Sound waves in air are longitudinal waves.
In a longitudinal wave, particles move perpendicular to the direction of wave propagation.
Light waves are examples of longitudinal waves.

Which of the statements given above is/are correct?

Official previous-year question

Verified 1 Aug 2026.

Options

A1 only
B2 only
C1 and 3 only
D1, 2 and 3

Did you get this right?

Solution

Correct Option

The correct option is (a).

Explanation

Waves are disturbances that transport energy. Based on the direction of particle oscillation relative to the direction of wave propagation, mechanical waves are classified into longitudinal and transverse waves.

Statement-wise Analysis

Statement 1 is Correct: Sound waves in air are longitudinal waves. They propagate through the medium as a series of compressions (high pressure) and rarefactions (low pressure).
Statement 2 is Incorrect: In a longitudinal wave, the particles of the medium oscillate parallel to the direction of wave propagation. It is in transverse waves that particles oscillate perpendicular to the direction of propagation.
Statement 3 is Incorrect: Light waves are electromagnetic waves and are transverse in nature. In light waves, the electric and magnetic fields oscillate perpendicular to the direction of the wave's travel.

Key Takeaway: Sound waves in fluids are longitudinal (parallel oscillation), whereas light waves are transverse (perpendicular oscillation).

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?

medium

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?

easy

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?

medium

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Correct Option

The correct option is (a).

Explanation

Statement-wise Analysis

Statement 1 is Correct: Sound waves in air are longitudinal waves. They propagate through the medium as a series of compressions (high pressure) and rarefactions (low pressure).
Statement 2 is Incorrect: In a longitudinal wave, the particles of the medium oscillate parallel to the direction of wave propagation. It is in transverse waves that particles oscillate perpendicular to the direction of propagation.
Statement 3 is Incorrect: Light waves are electromagnetic waves and are transverse in nature. In light waves, the electric and magnetic fields oscillate perpendicular to the direction of the wave's travel.

Key Takeaway: Sound waves in fluids are longitudinal (parallel oscillation), whereas light waves are transverse (perpendicular oscillation).