Sound Part 2: MCQs (Q26–Q50)
🔊 Sound – MCQs for Class 8 Science
Part 2: Q26–Q50
Q26. Sound waves are:
A) Longitudinal
B) Transverse
C) Electromagnetic
D) Both longitudinal and transverse
✅ Correct Answer: A) Longitudinal
Explanation:
- A) ✔ Particles vibrate parallel to direction of wave → longitudinal.
- B) Wrong: transverse waves = vibrations ⟂ direction.
- C) EM waves don’t need medium.
- D) Not correct in air.
Q27. The unit of loudness is:
A) Watt
B) Decibel
C) Newton
D) Joule
✅ Correct Answer: B) Decibel
Explanation:
- B) ✔ Loudness measured in decibels (dB).
- A, C, D – Other physical quantities.
Q28. Which of the following animals communicates using infrasound?
A) Bat
B) Dog
C) Elephant
D) Dolphin
✅ Correct Answer: C) Elephant
Explanation:
- C) ✔ Elephants use <20 Hz sounds to communicate long distances.
Q29. Ultrasonic waves are used in:
A) Sonography
B) Music production
C) Television
D) Telecommunication
✅ Correct Answer: A) Sonography
Explanation:
- A) ✔ Ultrasound scans inside body organs.
- B, C, D – Use audible/electromagnetic waves.
Q30. Which part of human ear collects sound waves?
A) Cochlea
B) Eardrum
C) Pinna
D) Ear canal
✅ Correct Answer: C) Pinna
Explanation:
- C) ✔ Pinna collects sound and directs to ear canal.
- A, B, D – Other ear parts.
Q31. The frequency of a tuning fork producing sound is 512 Hz. It means it makes:
A) 512 oscillations per second
B) 256 oscillations per second
C) 1 oscillation per second
D) 1024 oscillations per second
✅ Correct Answer: A) 512 oscillations per second
Explanation:
- Frequency = number of oscillations per second.
Q32. The time required to complete one vibration is called:
A) Frequency
B) Amplitude
C) Period
D) Wavelength
✅ Correct Answer: C) Period
Explanation:
- C) ✔ Period = reciprocal of frequency.
Q33. Sound travels faster in:
A) Solids
B) Liquids
C) Gases
D) Vacuum
✅ Correct Answer: A) Solids
Explanation:
- A) ✔ Solids have high density and elasticity → fastest sound speed.
Q34. The reflection of sound is called:
A) Echo
B) Refraction
C) Diffraction
D) Dispersion
✅ Correct Answer: A) Echo
Explanation:
- A) ✔ Echo = sound reflection heard after delay.
Q35. Echo is heard clearly only if the obstacle is at least:
A) 5 m away
B) 10 m away
C) 17 m away
D) 50 m away
✅ Correct Answer: C) 17 m away
Explanation:
- C) ✔ Sound travels 340 m/s. For echo, min. distance = 17 m (time ≥ 0.1 s).
Q36. Sound is a form of:
A) Light energy
B) Mechanical energy
C) Chemical energy
D) Thermal energy
✅ Correct Answer: B) Mechanical energy
Explanation:
- B) ✔ Sound produced by mechanical vibrations.
Q37. The maximum displacement of vibrating particles from mean position is called:
A) Amplitude
B) Frequency
C) Pitch
D) Period
✅ Correct Answer: A) Amplitude
Explanation:
- A) ✔ Amplitude decides loudness.
Q38. Sound is produced by:
A) Heating
B) Vibrations
C) Reflection
D) Refraction
✅ Correct Answer: B) Vibrations
Explanation:
- B) ✔ Vibrations of objects generate sound.
Q39. Which of the following is NOT an application of ultrasound?
A) Cleaning spiral tubes
B) Detecting cracks in metals
C) Cooking food
D) Scanning body organs
✅ Correct Answer: C) Cooking food
Explanation:
- C) ✔ Ultrasound cannot cook. It is used in scanning, cleaning, defect detection.
Q40. In a longitudinal wave, compressions and rarefactions are regions of:
A) Low and high pressure
B) High and low pressure
C) Same pressure
D) No pressure
✅ Correct Answer: B) High and low pressure
Explanation:
- B) ✔ Compression = high pressure, rarefaction = low pressure.
Q41. Which property of sound helps us to distinguish between two voices of same loudness?
A) Amplitude
B) Pitch
C) Quality or timbre
D) Frequency
✅ Correct Answer: C) Quality or timbre
Explanation:
- C) ✔ Quality differentiates sounds of same pitch and loudness.
Q42. A flute produces sound by:
A) Vibration of stretched string
B) Vibration of air column
C) Vibration of membrane
D) Electronic signals
✅ Correct Answer: B) Vibration of air column
Explanation:
- B) ✔ Wind instruments use vibrating air columns.
Q43. Which part of the ear vibrates when sound enters?
A) Pinna
B) Ear canal
C) Eardrum
D) Cochlea
✅ Correct Answer: C) Eardrum
Explanation:
- C) ✔ Eardrum vibrates and passes sound further inside.
Q44. What determines the loudness of a sound wave?
A) Frequency
B) Amplitude
C) Wavelength
D) Speed
✅ Correct Answer: B) Amplitude
Explanation:
- B) ✔ Larger amplitude = louder sound.
Q45. Which sound has a higher pitch?
A) Drum beat
B) Man’s voice
C) Whistle
D) Thunder
✅ Correct Answer: C) Whistle
Explanation:
- C) ✔ Whistle has high frequency → high pitch.
Q46. Which of the following musical instruments produces sound by vibrating strings?
A) Tabla
B) Flute
C) Veena
D) Drum
✅ Correct Answer: C) Veena
Explanation:
- C) ✔ Veena → plucked string instrument.
Q47. The sound cannot travel through:
A) Steel
B) Air
C) Water
D) Space
✅ Correct Answer: D) Space
Explanation:
- D) ✔ Vacuum cannot transmit sound.
Q48. The device used by visually impaired persons to read is based on:
A) Reflection of sound
B) Echo of sound
C) Vibration of strings
D) Electrostatic waves
✅ Correct Answer: B) Echo of sound
Explanation:
- B) ✔ Sonar-like devices use echoes for navigation/reading aids.
Q49. What is the function of cochlea in human ear?
A) Collects sound waves
B) Converts sound into electrical signals
C) Vibrates with sound
D) Reflects sound
✅ Correct Answer: B) Converts sound into electrical signals
Explanation:
- B) ✔ Cochlea converts mechanical sound into nerve impulses.
Q50. SONAR is used to detect:
A) Speed of light
B) Objects under water
C) Air pollution
D) Heat energy
✅ Correct Answer: B) Objects under water
Explanation:
- B) ✔ SONAR (Sound Navigation And Ranging) uses ultrasound to detect underwater objects.
Sound Class 8 MCQs, CBSE Class 8 Science MCQs, NCERT Class 8 Sound Questions, Online Learning Science MCQs, Important MCQs Class 8, cbse class 8 science sound mcqs with answers, ncert class 8 sound objective questions, important mcqs for class 8 sound board exams, online learning mcqs for class 8 science sound, chapter wise mcqs for class 8 science sound