Physics Class 10 — Chapter 2: Sound (Interactive Quiz)
English + Urdu (دو لسانی) — 60 MCQs with instant scoring • Practice for Sindh Board exams
Tip: use this quiz for timed practice and revision.
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1. Sound is a form of — (Choose the best option)1۔ آواز کس توانائی کی شکل ہے؟Correct — sound is mechanical energy (it needs a medium).Wrong — sound is mechanical energy and requires a medium to travel.
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2. Sound requires a ________ to travel.2۔ آواز کے سفر کے لیے کس چیز کی ضرورت ہوتی ہے؟Correct — sound needs a material medium (solid, liquid, or gas).Wrong — sound cannot travel through a vacuum; it needs a medium.
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3. Approximate speed of sound in air at 20°C is:3۔ ہوا میں 20°C پر آواز کی رفتار تقریباً کتنی ہے؟Correct — about 343 m/s at 20°C in dry air.Wrong — the accepted approximate value is 343 m/s at 20°C.
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4. Which of the following cannot transmit sound?4۔ مندرجہ ذیل میں سے کون آواز منتقل نہیں کر سکتا؟Correct — vacuum cannot transmit sound.Wrong — sound cannot travel through vacuum.
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5. The unit of frequency is:5۔ تعدد (frequency) کی اکائی کیا ہے؟Correct — frequency is measured in hertz (Hz).Wrong — frequency’s unit is hertz (Hz).
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6. Sound waves are:6۔ آواز کی لہریں کس نوعیت کی ہوتی ہیں؟Correct — sound in fluids/solids is longitudinal (compression & rarefaction).Wrong — sound waves in air are longitudinal waves.
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7. The pitch of sound depends on:7۔ آواز کی pitch کس چیز پر منحصر ہوتی ہے؟Correct — pitch relates to frequency (higher frequency → higher pitch).Wrong — pitch is linked to frequency, not amplitude.
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8. Loudness of a sound depends mainly on:8۔ آواز کی شدت (loudness) زیادہ تر کس پر منحصر ہوتی ہے؟Correct — loudness is related to amplitude (and energy of the wave).Wrong — amplitude (not frequency) influences loudness.
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9. Human audible frequency range is approximately:9۔ انسان عام طور پر کس فریکوئنسی رینج کو سن سکتا ہے؟Correct — typical human hearing: 20 Hz to 20,000 Hz (approx.).Wrong — standard audible range is roughly 20–20,000 Hz.
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10. Sound travels fastest in which of the following?10۔ مندرجہ ذیل میں آواز سب سے تیز کس میں سفر کرتی ہے؟Correct — sound speed is highest in solids, then liquids, then gases.Wrong — solids transmit sound faster than liquids and gases.
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11. Echo is a result of:11۔ گونج (echo) کس چیز کا نتیجہ ہے؟Correct — echo occurs when sound reflects from a surface and returns to the listener.Wrong — echo is due to reflection of sound waves.
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12. Minimum time gap between the original sound and echo for it to be heard separately is about:12۔ آواز اور گونج کے الگ سنائی دینے کے لیے کم از کم وقت کا فرق تقریباً کتنا ہونا چاہیے؟Correct — around 0.1 s (so echo needs a reflecting surface roughly 17 m away, one-way, at 343 m/s).Wrong — the typical threshold is about 0.1 s for a distinct echo.
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13. The speed of sound depends on:13۔ آواز کی رفتار کس پر منحصر کرتی ہے؟Correct — properties of the medium (density & elasticity) determine speed.Wrong — sound speed is governed by the medium, not the source’s frequency.
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14. Unit of sound intensity is:14۔ آواز کی شدت کی اکائی کیا ہے؟Correct — intensity measured in W/m²; loudness often given in decibels (dB).Wrong — intensity unit is W/m² (loudness measured in dB).
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15. Instrument used to measure loudness (sound level) is called:15۔ آواز کی بلند ی/سطح ناپنے والا آلہ کیا کہلاتا ہے؟Correct — sound level meter measures sound pressure level in dB.Wrong — the correct instrument is a sound level meter.
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16. Which frequency range is called infrasonic?16۔ کون سی فریکوئنسی رینج کو infra-sonic کہا جاتا ہے؟Correct — infrasonic waves have frequency below 20 Hz.Wrong — infrasonic < 20 Hz; audible is 20–20,000 Hz.
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17. Which frequency range is called ultrasonic?17۔ کون سی فریکوئنسی رینج کو ultra-sonic کہا جاتا ہے؟Correct — ultrasonic frequencies exceed 20 kHz (used in sonar, medical imaging).Wrong — ultrasonic > 20,000 Hz.
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18. Bats use which type of sound waves to navigate?18۔ چمگادڑ راستہ تلاش کرنے کے لیے کس نوعیت کی لہروں کا استعمال کرتی ہے؟Correct — bats use ultrasonic echoes (echolocation).Wrong — bats rely on ultrasonic sounds to navigate and catch prey.
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19. What is the relationship between wavelength (λ), frequency (f) and speed (v) of sound?19۔ لہردائری (wavelength)، فریکوئنسی اور رفتار کے درمیان کیا رشتہ ہے؟Correct — wave speed v equals frequency times wavelength.Wrong — correct formula is v = f × λ.
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20. If frequency increases while speed remains same, wavelength will:20۔ اگر فریکوئنسی بڑھے اور رفتار ایک جیسی رہے تو wavelength کیا ہوگا؟Correct — because v = fλ, if v constant and f↑ then λ↓.Wrong — wavelength decreases when frequency increases (if speed constant).
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21. When sound passes through a narrow opening and spreads, this phenomenon is called:21۔ جب آواز تنگ سوراخ سے گذر کر پھیلتی ہے تو اسے کیا کہتے ہیں؟Correct — diffraction is bending/spreading of waves around obstacles/openings.Wrong — spreading at openings is diffraction, not reflection/refraction.
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22. When two sound waves of slightly different frequencies meet, we hear beats. Beat frequency equals:22۔ جب دو آوازیں جن کی فریکوئنسی قریب قریب ہو ملتی ہیں تو ہم ‘beats’ سنتے ہیں۔ beat frequency کیا ہوگی؟Correct — beat frequency = |f1 − f2|.Wrong — beats frequency equals the absolute difference of the two frequencies.
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23. Reverberation is:23۔ Reverberation کیا ہے؟Correct — reverberation is many reflected sounds causing prolonged hearing.Wrong — reverberation is multiple reflections, not a single echo.
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24. Which material would you choose to reduce reverberation in a hall?24۔ ہال میں reverberation کم کرنے کے لیے آپ کون سا material استعمال کریں گے؟Correct — soft, porous materials absorb sound and reduce reverberation.Wrong — soft absorbers (curtains, foam) reduce reverberation; hard surfaces increase it.
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25. Doppler effect describes the change in:25۔ Doppler اثر کس چیز میں تبدیلی بیان کرتا ہے؟Correct — Doppler effect: observed frequency changes with relative motion.Wrong — Doppler affects perceived frequency, not amplitude per se.
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26. If a source approaches a stationary observer, the observed frequency will be:26۔ اگر ماخذ مبصر کی طرف آ رہا ہو تو سنا گیا فریکوئنسی کیا ہوگا؟Correct — approach → higher frequency (pitch seems higher).Wrong — when source moves towards observer, perceived frequency increases.
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27. Fundamental frequency or first harmonic of a string depends on:27۔ کسی تار کی بنیادی فریکوئنسی کن چیزوں پر منحصر کرتی ہے؟Correct — f1 ∝ (1/2L)√(T/μ) where L length, T tension, μ linear density.Wrong — fundamental depends on length, tension and mass per unit length, not color.
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28. A tuning fork produces 440 Hz. This property is called:28۔ ایک tuning fork 440 Hz پیدا کرتی ہے۔ اسے کیا کہتے ہیں؟Correct — 440 Hz indicates the frequency (A4 note).Wrong — 440 Hz refers to frequency/pitch, not loudness.
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29. If the amplitude of sound wave doubles, what happens to its intensity approximately?29۔ اگر صوتی لہرد کی amplitude دوگنی ہو جائے تو اس کی intensity قریباً کیا ہوگی؟Correct — intensity ∝ amplitude², so doubling amplitude → 4× intensity.Wrong — intensity scales with amplitude squared, so it becomes four times.
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30. Which of the following will increase the speed of sound in air?30۔ درج ذیل میں سے کون سی چیز ہوا میں آواز کی رفتار بڑھائے گی؟Correct — speed of sound in air increases with temperature.Wrong — warmer air increases sound speed; humidity has a minor effect.
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31. Which of these is NOT an application of ultrasound?31۔ ذیل میں سے کون سی چیز الٹراساؤنڈ کا استعمال نہیں ہے؟Correct — microwave ovens use microwaves, not ultrasound.Wrong — microwaves are different from ultrasound; ultrasound used in sonography, cleaning.
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32. Which surface will reflect sound the best?32۔ کون سی سطح آواز کو سب سے بہتر طریقے سے منعکس کرے گی؟Correct — hard smooth surfaces reflect sound well; soft materials absorb sound.Wrong — hard, smooth surfaces yield strong reflections; soft surfaces absorb.
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33. In which medium is sound speed the slowest among these?33۔ ان میں سے کس مادّہ میں آواز کی رفتار سب سے کم ہوتی ہے؟Correct — sound travels slowest in gases like air compared to liquids and solids.Wrong — among listed, air (a gas) gives lowest speed of sound.
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34. Which is loudness measured in decibels typical of normal conversation?34۔ عام گفتگو کی عام آواز کتنے decibel کے قریب ہوتی ہے؟Correct — normal conversation ~60–70 dB; threshold of pain ~120 dB.Wrong — normal conversation is roughly 60–70 dB.
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35. A sound source of frequency 520 Hz and another of 528 Hz are played together. What is beat frequency?35۔ اگر دو سورس کی فریکوئنسی 520 Hz اور 528 Hz ہوں تو beat frequency کیا ہوگی؟Correct — beat frequency = |528 − 520| = 8 Hz.Wrong — beats = difference of frequencies (8 Hz).
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36. A sound wave of frequency 1000 Hz in air has wavelength close to (v ≈ 340 m/s):36۔ ہوا میں 1000 Hz کی آواز کی wavelength تقریبا کتنی ہوگی؟ (v ≈ 340 m/s)Correct — λ = v/f = 340 / 1000 = 0.34 m.Wrong — wavelength = v/f, so around 0.34 m for 1000 Hz.
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37. Which of these affects both pitch and wavelength simultaneously?37۔ مندرجہ ذیل میں سے کون سی چیز pitch اور wavelength دونوں کو بیک وقت متاثر کرتی ہے؟Correct — frequency determines pitch; for given speed, frequency also sets wavelength (v = fλ).Wrong — frequency directly affects pitch and, if speed fixed, wavelength.
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38. Which of the following is true about sound reflection?38۔ آواز کی عکاسی (reflection) کے بارے میں کون سی بات درست ہے؟Correct — law of reflection applies: angle in = angle out (for plane surfaces).Wrong — reflected wave obeys angle of incidence equals angle of reflection.
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39. Which statement about sound energy is correct?39۔ آواز کی توانائی کے بارے میں کون سی بات درست ہے؟Correct — absorbed sound energy dissipates as heat.Wrong — absorption converts sound energy to other forms like heat.
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40. Which of these devices converts sound into electrical signals?40۔ کون سا آلہ آواز کو برقی سگنلز میں تبدیل کرتا ہے؟Correct — microphone converts pressure variations into electrical signals.Wrong — microphone is the transducer converting sound to electrical signals.
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41. Which of the following increases when sound intensity increases?41۔ جب آواز کی intensity بڑھتی ہے تو درج ذیل میں سے کون سی چیز بڑھتی ہے؟Correct — intensity relates to energy per area and affects perceived loudness.Wrong — intensity primarily affects loudness rather than pitch or frequency.
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42. A siren frequency seems lower to an observer if the siren is —42۔ اگر سائرن مبصر سے دور جا رہا ہو تو مبصر اسے کس طرح محسوس کرے گا؟Correct — receding source → observed frequency decreases (Doppler effect).Wrong — a moving away source lowers the observed frequency.
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43. Which of these animals use infrasound for communication?43۔ کن جانوروں کی مواصلت میں infra-sonic آواز کا استعمال پایا جاتا ہے؟Correct — elephants use infrasonic calls to communicate over long distances.Wrong — elephants emit infrasonic signals (<20 Hz) for long-range communication.
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44. Resonance occurs when:44۔ تناو (resonance) کب ہوتا ہے؟Correct — resonance amplifies oscillations when driving frequency matches natural frequency.Wrong — resonance arises when driving and natural frequencies match.
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45. If two identical tuning forks are tuned and one is struck, the other starts vibrating due to:45۔ اگر دو یکساں tuning fork رکھی ہوں اور ایک کو مارا جائے تو دوسرا کیوں کانپنے لگتا ہے؟Correct — vibrations of the struck fork force the other into vibration at same frequency (resonance).Wrong — this is resonance/forced vibration, not electricity or chemistry.
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46. In open-open pipe, fundamental wavelength equals:46۔ ایک کھلے دونوں سروں والی نالی (open-open pipe) میں بنیادی wavelength کیا ہوتی ہے؟Correct — for open-open pipe fundamental λ = v/f (or length L = λ/2).Wrong — open-open pipe fundamental: L = λ/2 so λ = 2L and v = fλ → λ = v/f.
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47. Ultrasound frequency used in medical imaging is typically about:47۔ طبی تشخیص میں استعمال ہونے والی الٹراساؤنڈ کی عمومی فریکوئنسی تقریبا کتنی ہوتی ہے؟Correct — medical ultrasound commonly uses MHz range (1–15 MHz).Wrong — medical ultrasound is in MHz frequencies, much higher than kHz.
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48. Echo location resolution depends on which property of the pulse?48۔ echo location (مثلاً sonar) کی resolution کس خاصیت پر منحصر ہے؟Correct — shorter pulses (larger bandwidth) → better range resolution in sonar/ultrasound.Wrong — temporal pulse width/bandwidth controls resolution, not color.
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49. Sound absorption coefficient of a material is a measure of its ability to:49۔ کسی مادّہ کا sound absorption coefficient کس چیز کی پیمائش ہے؟Correct — higher absorption coefficient means more sound energy converted to heat (less reflection).Wrong — absorption coefficient indicates how much sound is absorbed, not reflected.
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50. Which one is an example of longitudinal wave among the following?50۔ درج ذیل میں سے longitudinal wave کی مثال کون سی ہے؟Correct — sound waves in air are longitudinal waves (compressions & rarefactions).Wrong — sound in air is longitudinal; light & EM waves are transverse.
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51. Wavelength of a sound wave decreases if —51۔ صوتی لہرد کی wavelength کب کم ہوتی ہے؟Correct — λ = v/f, so increasing f (v constant) reduces λ.Wrong — wavelength inversely relates to frequency (if speed is fixed).
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52. Which of the following is true for ultrasound used in imaging?52۔ تصویری الٹراساؤنڈ کے بارے میں کون سی بات درست ہے؟Correct — imaging uses MHz-range ultrasound for fine detail.Wrong — ultrasound used in imaging is in the MHz range and not audible.
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53. The ear converts sound waves into nerve impulses in which part?53۔ کان آواز کو عصبی اشاروں میں کس حصے میں تبدیل کرتا ہے؟Correct — cochlea transforms mechanical vibrations into nerve impulses.Wrong — cochlea (inner ear) contains hair cells that transduce vibrations to neural signals.
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54. A sound wave loses energy as it travels because of:54۔ آواز سفر کے دوران توانائی کیوں کھو دیتی ہے؟Correct — absorption and scattering in medium convert sound energy to heat, reducing intensity.Wrong — energy loss mainly due to absorption, not frequency change.
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55. Which property of sound is most affected when moving from warm air to cold air?55۔ گرم ہوا سے سرد ہوا میں منتقل ہونے پر آواز کی کون سی خصوصیت سب سے زیادہ متاثر ہوتی ہے؟Correct — sound speed decreases in colder air; frequency of source doesn’t change.Wrong — temperature primarily affects speed; frequency remains same for stationary sources.
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56. Sound in a pipe closed at one end has only —56۔ ایک سر بند نالی میں آواز کے harmonics کیسے ہوتے ہیں؟Correct — closed-open pipe supports odd harmonics (1st, 3rd, 5th…).Wrong — closed at one end supports odd harmonics only.
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57. Musical instruments produce sound mainly by creating —57۔ موسیقی آلات عام طور پر آواز کیسے پیدا کرتے ہیں؟Correct — instruments support standing waves (strings, air columns) producing musical notes.Wrong — musical sounds are produced by resonant standing waves, not random noise.
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58. Frequency of a note is 880 Hz. What is the octave below this note?58۔ اگر ایک نوٹ کی فریکوئنسی 880 Hz ہو تو اس سے ایک اکتاو نیچے نوٹ کی فریکوئنسی کیا ہوگی؟Correct — one octave lower is half the frequency: 880/2 = 440 Hz.Wrong — octave down halves the frequency (440 Hz).
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59. What happens to intensity if distance from a point source doubles (ideal point source)?59۔ اگر نقطہ ماخذ سے فاصلہ دوگنا ہو جائے تو intensity کیا ہوگا؟Correct — intensity ∝ 1/r² for point sources; doubling r → intensity 1/4.Wrong — point source intensity follows inverse square law (1/4 when distance doubles).
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60. Which of the following is measured with an oscilloscope for sound?60۔ آواز کی کون سی خصوصیت کو oscilloscope پر ناپا جا سکتا ہے؟Correct — oscilloscope displays waveform vs. time for electrical signal from microphone.Wrong — oscilloscope shows waveform (time-domain) of sound converted to electrical signal.
Answer Key (Q1 → Q60):
1-B, 2-B, 3-C, 4-D, 5-C, 6-B, 7-B, 8-A, 9-C, 10-C,
11-B,12-C,13-A,14-C,15-B,16-C,17-B,18-B,19-B,20-B,
21-A,22-D,23-A,24-C,25-A,26-B,27-A,28-C,29-B,30-C,
31-A,32-D,33-A,34-B,35-A,36-C,37-B,38-D,39-B,40-C,
41-B,42-C,43-A,44-B,45-A,46-C,47-D,48-C,49-B,50-B,
51-A,52-C,53-D,54-B,55-A,56-C,57-A,58-B,59-A,60-B
11-B,12-C,13-A,14-C,15-B,16-C,17-B,18-B,19-B,20-B,
21-A,22-D,23-A,24-C,25-A,26-B,27-A,28-C,29-B,30-C,
31-A,32-D,33-A,34-B,35-A,36-C,37-B,38-D,39-B,40-C,
41-B,42-C,43-A,44-B,45-A,46-C,47-D,48-C,49-B,50-B,
51-A,52-C,53-D,54-B,55-A,56-C,57-A,58-B,59-A,60-B
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