Kerala SSLC · Physics · Class 10

Sound: Important Questions with Answers

These are 10 important multiple-choice questions from the Kerala SSLC Physics chapter “Sound” (Kerala SCERT syllabus). Each one shows the correct answer and a short explanation of why it is right. Try answering before you read the answer. ExamSummary has 10 practice questions on this chapter in total.

  1. Q1.Sound propagates through a medium as _______ waves.

    • A)Transverse
    • B)Longitudinal
    • C)Electromagnetic
    • D)Surface

    Answer: B) Longitudinal

    Sound waves are mechanical waves where particle displacement is parallel to the direction of wave propagation, making them longitudinal. Unlike light, sound cannot travel through a vacuum and requires a material medium.

  2. Q2.In which of the following media does sound travel the fastest?

    • A)Air
    • B)Water
    • C)Steel
    • D)Vacuum

    Answer: C) Steel

    Sound travels fastest in solids because the particles are closely packed, allowing vibrations to transfer quickly. It travels slower in liquids and slowest in gases, while it cannot travel in a vacuum at all.

  3. Q3.The audible range of human hearing extends from:

    • A)20 Hz to 200 Hz
    • B)20 Hz to 20,000 Hz
    • C)200 Hz to 2,000 Hz
    • D)Below 20 Hz only

    Answer: B) 20 Hz to 20,000 Hz

    Humans can typically hear frequencies between 20 Hertz and 20,000 Hertz. Sounds below 20 Hz are called infrasonic, while those above 20,000 Hz are called ultrasonic.

  4. Q4.A boy claps his hands near a cliff and hears the echo after 2 seconds. If the speed of sound is 340 m/s, what is the distance to the cliff?

    • A)340 meters
    • B)680 meters
    • C)170 meters
    • D)510 meters

    Answer: A) 340 meters

    The total distance traveled by sound is speed multiplied by time (340 × 2 = 680 m). Since the sound goes to the cliff and returns, the distance to the cliff is half of the total distance, which is 340 meters.

  5. Q5.Which property of sound determines its 'shrillness' or pitch?

    • A)Amplitude
    • B)Speed
    • C)Frequency
    • D)Wavelength

    Answer: C) Frequency

    Pitch is directly related to the frequency of the sound wave; higher frequency results in a higher pitch or shriller sound. Amplitude determines the loudness, not the pitch.

  6. Q6.SONAR technology used in submarines operates based on the principle of:

    • A)Refraction of sound
    • B)Reflection of sound
    • C)Diffraction of sound
    • D)Interference of sound

    Answer: B) Reflection of sound

    SONAR (Sound Navigation and Ranging) works by sending ultrasonic pulses and detecting the reflected echoes from underwater objects. This relies on the reflection property of sound waves.

  7. Q7.If the amplitude of a sound wave is doubled, how does the loudness change?

    • A)It becomes double
    • B)It becomes half
    • C)It becomes four times
    • D)It remains the same

    Answer: C) It becomes four times

    Loudness is directly proportional to the square of the amplitude of the vibration. Therefore, doubling the amplitude results in the loudness increasing by a factor of four.

  8. Q8.Which type of sound waves are commonly used in medical ultrasound imaging?

    • A)Infrasonic waves
    • B)Audible sound waves
    • C)Ultrasonic waves
    • D)Radio waves

    Answer: C) Ultrasonic waves

    Ultrasonic waves have high frequencies beyond human hearing, allowing them to penetrate tissues and reflect off internal organs safely. This makes them ideal for non-invasive medical imaging like scanning fetuses.

  9. Q9.Why is it impossible to hear a bell ringing inside a sealed vacuum jar?

    • A)Light cannot enter the jar
    • B)There are no particles to transmit vibrations
    • C)The temperature is too low
    • D)Sound travels too slowly in air

    Answer: B) There are no particles to transmit vibrations

    Sound is a mechanical wave that requires a material medium (solid, liquid, or gas) to propagate vibrations from the source to the ear. In a vacuum, there are no particles to vibrate and carry the sound energy.

  10. Q10.According to the wave equation v = f lambda, if the frequency of a sound wave increases while speed remains constant, the wavelength will:

    • A)Increase
    • B)Decrease
    • C)Remain unchanged
    • D)Become infinite

    Answer: B) Decrease

    Frequency and wavelength are inversely proportional when the speed of the wave is constant. Therefore, an increase in frequency necessitates a decrease in wavelength to maintain the constant speed.

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