- The same concept or a question is asked with different angles to clear Doubts.
- Topic Specific, with a mix of easy, medium, and high-level questions for strong subject clarity .
📘 Welcome
Hi User, you have selected Read Mode.
This is Time Free Mode for your convenience to understand every question as per your Ease and Time.
Here You get Answer and Details button. After mastering this mode, you can go for a test with Test Mode on the main page designed especially with Exam Features.
This is Time Free Mode for your convenience to understand every question as per your Ease and Time.
Here You get Answer and Details button. After mastering this mode, you can go for a test with Test Mode on the main page designed especially with Exam Features.
Q1. Intensity and loudness of sound are
Intensity is a physical quantity that can be measured objectively—it is the amount of sound energy passing per second through unit area. Loudness, on the other hand, is the physiological sensation perceived by the ear, which depends on the sensitivity of the ear and the listener’s perception. Loudness is subjective, while intensity is objective. Both are not measured in Hz (hertz is the unit of frequency). They are not the same, and they depend on amplitude—larger amplitude means greater intensity and loudness.
Q2. If a clap echo is heard after 2 s and speed of sound is 346 m/s, distance to cliff is
The echo is heard after sound travels to the cliff and back. Total distance travelled = speed × time = 346 × 2 = 692 m. This is twice the distance to the cliff. So, distance to the cliff = 692 / 2 = 346 m. The other options are incorrect calculations.
Q3. A thunder is heard later than lightning because
Light travels at about 3 × 10⁸ m/s, while sound travels only at about 344 m/s in air. Since light is much faster, we see the lightning flash almost instantly. The sound of thunder travels much slower, so it reaches us later, causing the delay. Sound is slower than light, not faster.
Q4. Sonic boom is caused when object moves
A sonic boom is produced when an object travels through air at a speed greater than the speed of sound (supersonic speed). The object creates shock waves that merge into a single loud boom. Moving slower than sound, very slowly, or at the speed of light does not produce a sonic boom.
Q5. Speed of sound increases with
The speed of sound in a gas increases with an increase in temperature because the molecules move faster and transmit vibrations more quickly. In air, the speed increases by about 0.6 m/s for every 1°C rise in temperature. Decrease in temperature would decrease the speed of sound, and loudness does not affect speed.
Q6. If a sound has a frequency of 2 kHz and wavelength 0.35 m, its speed is
Speed of sound v = frequency (ν) × wavelength (λ). Frequency = 2 kHz = 2000 Hz. Wavelength = 0.35 m. v = 2000 × 0.35 = 700 m/s. The other options are incorrect calculations.
Q7. Minimum distance of obstacle for hearing echo if speed of sound is 344 m/s
The human ear can distinguish two sounds if the time interval between them is at least 0.1 s. For echo, the sound must travel to the obstacle and back in 0.1 s. Total distance = speed × time = 344 × 0.1 = 34.4 m. This is twice the distance to the obstacle. So, minimum distance = 34.4 / 2 = 17.2 m.
Q8. Repeated echoes in a hall result in
Repeated reflections of sound in a hall or enclosed space result in reverberation. The sound persists even after the source stops producing it, due to multiple reflections. This is different from a single echo (which is a distinct repetition) and from noise or sonic boom.
Q9. Reflection of sound obeys
Like light, sound also obeys the laws of reflection: the incident wave, reflected wave, and the normal all lie in the same plane, and the angle of incidence equals the angle of reflection. This is the law of reflection. Refraction, Newton’s law, and diffraction are different phenomena.
Q10. Loudness of a sound is highest when
Loudness is directly related to the amplitude of vibration. A larger amplitude means more energy in the wave, which produces a louder sound. Frequency determines pitch, wavelength is related to frequency, and speed is determined by the medium. Loudness depends on amplitude, not on frequency, wavelength, or speed directly.
Q11. Echo occurs due to
An echo is the reflected sound wave that returns to the listener after striking a hard surface like a cliff or wall. It is a direct result of the reflection of sound waves. Absorption would reduce sound, diffraction causes bending, and refraction changes direction but does not produce echoes.
Q12. Clapping near a cliff produces echo after 3 s. If speed of sound is 342 m/s, distance of cliff is
The echo is heard after the sound travels to the cliff and back. Total distance travelled = speed × time = 342 × 3 = 1026 m. This is twice the distance to the cliff. So, distance to the cliff = 1026 / 2 = 513 m. The other options are incorrect.
Q13. Time taken by a sound to travel 1.5 km at 700 m/s is
Time = Distance / Speed. Distance = 1.5 km = 1500 m. Speed = 700 m/s. Time = 1500 / 700 = 2.14 s ≈ 2.1 s. The other options are incorrect calculations.
Q14. Frequency of sound wave is independent of
Frequency is determined by the vibrating source and does not change when sound travels from one medium to another. It is independent of amplitude, which affects loudness. Wavelength and speed change with the medium, but frequency remains constant. So, frequency is independent of amplitude.
Q15. Loudhailers, horns, and trumpets are examples of
Loudhailers, horns, and trumpets use the principle of reflection of sound to direct sound in a particular direction. They are designed to focus sound and prevent it from spreading in all directions, thus increasing the intensity of sound in the forward direction. They are not echo producers or sonic boom generators.
Q16. To hear a distinct echo, time interval between original and reflected sound must be at least
The human ear can distinguish two sounds if the time interval between them is at least 0.1 seconds. If the reflected sound reaches the ear within less than 0.1 s, it merges with the original sound and is not heard as a distinct echo. This is the minimum time required for a distinct echo.
Q17. Loudness and intensity are
Intensity is the physical measure of sound energy (power per unit area), while loudness is the physiological perception of that intensity by the ear. Loudness is a subjective response, whereas intensity is an objective physical quantity. They are not measured in Hz, not exactly the same, and not directly related to pitch.
Q18. Wavelength and frequency are related to speed as
The speed of a wave (v) is equal to the product of its wavelength (λ) and frequency (ν). This is the fundamental wave equation: v = λν. The other options are incorrect relationships. This equation applies to all types of waves, including sound.
Q19. Reverberation is
Reverberation is the persistence of sound due to multiple reflections in an enclosed space. It is not an increase in pitch, a decrease in loudness, or a single echo. It is the repeated reflection that causes sound to linger even after the source has stopped.
Q20. Wavelength is the distance between
In a sound wave (longitudinal wave), wavelength is the distance between two consecutive compressions or two consecutive rarefactions. In a transverse wave, it would be the distance between two consecutive peaks or troughs. The distance between a peak and trough is half a wavelength.
Q21. Speed of sound decreases from
Sound travels fastest in solids, slower in liquids, and slowest in gases. This is because particles are more closely packed in solids, allowing faster transmission of vibrations. So the speed decreases from solids to liquids to gases. The other options are incorrect.
Q22. In the formula v = λ × ν, ν represents
In the wave equation v = λν, ν (nu) represents frequency. It is the number of oscillations per second, measured in hertz (Hz). λ represents wavelength, and v represents speed. Time period is T, and amplitude is A.
Q23. Which sound has a higher pitch?
Pitch is determined by frequency. A car horn generally produces a higher frequency sound compared to a guitar (depending on the note played). However, this is a generalisation. The question asks which sound has a higher pitch—a car horn typically has a higher pitch than the low notes of a guitar. Pitch does not depend on distance, and both are not the same.
Q24. Shock waves from sonic boom are
Shock waves from a sonic boom carry high energy. They are powerful pressure waves that can cause damage to structures and are heard as a loud boom. They are not low energy, not undetectable, and are different from an echo.
Q25. Rolling thunder is caused by
Rolling thunder is heard as a prolonged rumbling sound because the thunder undergoes multiple successive reflections between clouds, mountains, and the ground. These repeated reflections reach the ear at slightly different times, creating the characteristic rolling effect. It is not due to low pitch, amplitude increase, or a single reflection.
Q26. Shock waves from a supersonic aircraft produce
When an aircraft travels faster than the speed of sound (supersonic), it produces shock waves that merge into a single loud sound called a sonic boom. This is a very powerful sound that can be heard on the ground. It is not an echo, noise only, or reverberation.
Q27. Loudspeakers and trumpets work on the principle of
Loudspeakers and trumpets use the principle of reflection of sound to direct sound waves in a particular direction. They are designed to reflect sound and focus it, increasing the intensity in the forward direction. They do not work on reverberation, light transmission, or absorption.
Q28. The amount of sound energy passing per second through unit area is called
Intensity is defined as the amount of sound energy passing through a unit area perpendicular to the direction of propagation per second. Pitch is the perception of frequency, frequency is the number of oscillations per second, and amplitude is the maximum displacement. Intensity is the correct term.
Q29. An echo is heard due to
An echo is the result of the reflection of sound waves from a hard surface. When sound waves strike a surface like a cliff, wall, or mountain, they are reflected back to the listener, creating an echo. Interference, diffraction, and absorption do not produce echoes.
Q30. Angle of incidence for sound reflection is
Just like light, sound follows the law of reflection: the angle of incidence (between the incident wave and the normal) is always equal to the angle of reflection (between the reflected wave and the normal). This is a fundamental property of wave reflection. The angles are equal, not greater, less, or zero.
Q31. Low pitch sound has
Pitch is directly related to frequency. A low-pitched sound has a low frequency. High frequency gives high pitch. Wavelength and amplitude do not determine pitch directly. So, low pitch means low frequency.
Q32. Supersonic speed is when an object moves
Supersonic speed means moving at a speed greater than the speed of sound in that medium. An object moving faster than sound produces shock waves and a sonic boom. Slower than sound is subsonic, and exactly at sound speed is sonic. Faster than light is not supersonic.
Q33. Speed of sound in distilled water at 25°C is approximately
The speed of sound in distilled water at 25°C is approximately 1498 m/s. This is faster than in air (about 346 m/s) but slower than in solids like steel. 1531 m/s is close but slightly high, 346 m/s is the speed in air, and 1207 m/s is incorrect.
Q34. Excessive reverberation in a hall is reduced by
Excessive reverberation can be reduced by using sound-absorbing materials like compressed fibreboard, rough plaster, draperies, and acoustic tiles. These materials absorb sound and prevent excessive reflections. Smooth walls and hard surfaces increase reflection, and large open windows may allow sound to escape but do not reduce reverberation effectively.
Q35. The speed of sound in a medium
The speed of sound in a given medium is almost constant for all frequencies, as long as the medium’s properties (temperature, pressure, density) are constant. It does not vary with frequency or loudness. Changes in the medium (like temperature or pressure) affect the speed.
Q36. In the formula v = λ × ν, λ represents
In the wave equation v = λν, λ (lambda) represents wavelength, which is the distance between two consecutive compressions or rarefactions. ν represents frequency, and v represents speed. Time period is T, and amplitude is A.
Q37. In a megaphone, sound is directed forward to
A megaphone directs sound forward by reflecting sound waves and preventing them from spreading in all directions. This increases the intensity of sound in the forward direction. It does not produce echo, reduce amplitude, or increase frequency.
Q38. Speed of sound in steel is about
The speed of sound in steel is approximately 5960 m/s, which is much faster than in air (344 m/s) or water (1500 m/s). This is because solids have closely packed particles that transmit vibrations quickly. The other options are incorrect values.
Q39. High pitch sound has
Pitch is directly related to frequency. A high-pitched sound has a high frequency. Amplitude affects loudness, wavelength is inversely related to frequency, and intensity is related to amplitude. So, high pitch means high frequency.
Q40. Materials used to reduce reverberation include
Materials that absorb sound are used to reduce reverberation. These include compressed fibreboard, rough plaster, draperies, acoustic tiles, and carpets. Glass sheets, steel plates, and concrete reflect sound and increase reverberation.
Q41. Time interval between sound and echo depends on
The time interval between the original sound and the echo depends on the distance to the reflecting obstacle and the speed of sound. The formula is time = 2 × distance / speed of sound. Loudness, wavelength, and speed of light are not factors in this calculation.
Q42. Sonic boom can
A sonic boom is a high-energy shock wave that can be powerful enough to shatter glass, cause structural damage, and produce a very loud sound. It does not cause earthquakes, reduce sound, or affect the speed of light.
Q43. Formula for speed of sound is
The formula for the speed of sound (or any wave) is v = λ × ν, where v is speed, λ is wavelength, and ν is frequency. The other options are incorrect. T is time period, not a factor in this formula.
Q44. Reflection of sound requires
Reflection of sound requires a large solid or liquid obstacle (like a wall, cliff, or building) that can reflect the sound waves back. A transparent medium or vacuum does not reflect sound effectively, and small objects do not produce noticeable echoes.
Q45. Speed of sound is defined as
Speed of sound is defined as the distance travelled by a sound wave per unit time. It is given by the formula v = λ × ν, but the basic definition is distance/time. Amplitude and loudness do not define speed.
Q46. The speed of sound in air at 22°C is approximately
The speed of sound in air at 22°C is approximately 344 m/s. At 0°C, it is about 331 m/s. At 25°C, it is about 346 m/s. So at 22°C, the value is approximately 344 m/s. 400 m/s is too high.
Q47. The speed of sound in air at 0°C is approximately
The speed of sound in air at 0°C is approximately 331 m/s. At higher temperatures, the speed increases (about 344 m/s at 22°C and 346 m/s at 25°C). 300 m/s is too low.
Q48. Megaphones are designed to
Megaphones are designed to direct sound in a particular direction by reflecting sound waves and preventing them from spreading out. This increases the intensity in the forward direction. They do not change frequency, absorb sound, or amplify without direction.
Q49. Intensity of sound is the
Intensity of sound is defined as the amount of sound energy passing through a unit area perpendicular to the direction of propagation per second. It is a physical quantity measured in watts per square metre (W/m²). Loudness is the response of the ear, frequency is a different property, and amplitude is the maximum displacement.
Q50. Sound cannot travel in
Sound cannot travel in a vacuum because there are no particles to vibrate and carry the sound wave. Sound is a mechanical wave and requires a material medium (solid, liquid, or gas) to propagate. Steel, air, and water are all media through which sound can travel.