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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 351. |
Define the term trough. |
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Answer» Trough: A trough is a point where the amplitude of a wave is minimum in a transverse wave. |
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| 352. |
What is crest? |
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Answer» Crest: Crest is a point where the amplitude of a wave is maximum in a transverse wave. |
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| 353. |
Define rarefaction. |
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Answer» Rarefaction: Rarefaction is the region where density, as well as the pressure of particles in the medium, is low. |
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| 354. |
What is tuning fork? |
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Answer» Tuning fork: A tuning fork is an acoustic resonator. It is a steel bar, bent in U-shape, with a handle at the bend. It resonates at a specific constant pitch when set into vibration by a string with a rubber hammer. |
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| 355. |
What is Compression? |
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Answer» Compression: Compression is the region where density, as well as the pressure of particles in the medium, is high. |
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| 356. |
The formula for speed of a transverse wave on a stretched spring is …………(m = linear mass density, T = tension in Spring)(A) v = \(\sqrt{\frac{m}{T}}\)(B) v = \(\sqrt{\frac{T}{m}}\)(C) v = \((\frac{m}{T})^\frac{3}{2}\)(D) v = \((\frac{T}{m})^\frac{3}{2}\) |
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Answer» Correct option is: (B) v = \(\sqrt{\frac{T}{m}}\) |
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| 357. |
Transverse waves involves change in …………. of the medium. A) density B) shape C) velocity D) temperature |
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Answer» Correct option is B) shape |
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| 358. |
Wavelength of the transverse wave is 30 cm. If the particle at some instant has displacement 2 cm, find the displacement of the particle 15 cm away at the same instant.(A) 2 cm (B) 17 cm(C) -2 cm (D) -17 cm |
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Answer» Correct option is: (C) -2 cm |
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| 359. |
Define transverse wave. |
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Answer» Transverse wave: If the particles of the medium vibrate perpendicular to the direction of the wave, then the wave ¡s called a transverse wave. |
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| 360. |
If pressure of air gets doubled at constant temperature then velocity of sound in air ………… .(A) gets doubled (B) remains unchanged (C) √2 times initial velocity (D) becomes half |
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Answer» (B) remains unchanged |
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| 361. |
In a transverse wave, are regions of negative displacement. (A) rarefactions (B) compressions (C) crests (D) troughs |
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Answer» Correct option is: (D) troughs |
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| 362. |
BladeVibrationsAmplitudeA15000.005 mB10000.05 inC1000.01 inFrom above table, which blade has more pitch? A) A B) B C) C D) All are equal |
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Answer» Correct option is A) A |
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| 363. |
Find the odd one out from the parts of speech organs. A) Vocal cards B) Lips C) TongueD) Ear |
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Answer» Correct option is D) Ear |
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| 364. |
How many times is a car horn more powerful than normal conversation? |
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Answer» The decibel rating of car horn = 110 dB The decibel rating of normal conversation = 60 dB The number of times a car horn more powerful than normal conversation = 105 times {110 – 60 = 50 which is taken as 105} (The explanation beyond our syllabus. It is based on logarithms) |
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| 365. |
The intensity of sound of car horn is ……… dB. A) 140 B) 110 C) 60 D) 140 |
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Answer» Correct option is B) 110 |
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| 366. |
The intensity of sound of jet engine ……… dB. A) 140 B) 120 C) 60 D) 80 |
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Answer» Correct option is B) 120 |
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| 367. |
The speed of sound in water is 1. 332 m 2. 1500 m 3. 5000 m s 4. 1000 m s |
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Answer» The speed of sound in water is 2. 1500 m |
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| 368. |
Calculate the minimum distance in air required between the source of sound and the obstacle to hear an echo. Take speed of sound in air = 350 m s-1 |
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Answer» Velocity = 2D/Time 350 = 2 × D/ 0.1 D = 350 × 0.1 / 2 = 17.5 m |
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| 369. |
A man standing 25 m away from a wall produces a sound and receives the reflected sound. (a) Calculate the time after which he receives the reflected sound if the speed of the sound in air is 350 m s-1. (b) will the man be able to hear a distinct echo? Explain the answer. |
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Answer» (a) Velocity = 2D/Time Time = 2 × 25 / 350 = 0.143 seconds (b) Yes, because the reflected sound reaches the man 0.1 second after the original sound is heard and the original sound persists only for 0.1 second. |
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| 370. |
1. What is meant by an echo? Mention one important condition that is necessary for an echo to be heard distinctly. 2. Mention one important use of echo. |
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Answer» 1. The sound heard after reflection from a rigid obstacle (such as a cliff, a hillside, wall of building, edge of a forest etc.) is called an echo. An echo is heard only if the distance between the person producing the sound and the rigid obstacle is long enough to allow the reflected sound to reach the person atleast 0.1 second after the original sound is heard. 2. Sound ranging and echo depth sounding. Echos are also . used by geologists for mineral prospecting. |
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| 371. |
What should be the minimum distance between source and reflector in water so that echo is heard distinctly?(The speed of sound in water = 1400 m s-1) |
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Answer» Velocity = 2D/Time 1400 = 2 × D/ 0.1 D = 1400 × 0.1/ 2 = 70 m |
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| 372. |
Wavelength is measured in 1. kg 2. second 3. litre 4. metre |
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Answer» Wavelength is measured in 4. metre |
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| 373. |
Explain how the speed of sound can be determined by the method of echo. |
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Answer» Sound is produced from a place at a known distance say, d at least 50 m from the reflecting surface. The time interval t in which the echo reaches the place from where the sound was produced, is noted by a stop watch having the least count 0.01 s. then the speed of sound is calculated by using the following relation V = total distance travelled / time interval = 2d/t m/s |
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| 374. |
State two applications of echo. |
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Answer» The applications of echo: (i) Dolphins detect their enemy and obstacles by emitting the ultrasonic waves and hearing their echo. (ii) In medical science, the echo method of ultrasonic waves is used for imaging the human organs such as the liver, gall bladder, uterus, womb etc. This is called ultrasonography. |
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| 375. |
State two differences between the light and sound waves. |
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Answer» (i) The light waves can travel in vacuum while sound waves need a material medium for propagation. (ii) The light waves are electromagnetic waves while sound waves are the mechanical waves. |
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| 376. |
A man is standing at a distance of 12 m from a cliff. Will he be able to hear a clear echo? Give a reason for your answer. |
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Answer» t = 2d/V = 2 × 12/340 = 24/340 < 0.1 seconds so the man will not be able to hear the echo. This is because the sensation of sound persists in our ears for about 0.1 second after the exciting stimulus ceases to act. |
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| 377. |
To change a loud sound into feeble sound, we decrease its: (A) amplitude (B) wavelength (C) frequency (D) velocity |
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Answer» The answer is (A) amplitude |
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| 378. |
At `20^(@)C`, the minimum distance of a person from a sound reflecting surface to hear an echo is:A. 12.2mB. 17.2mC. 15.2mD. 34.4m |
| Answer» Correct Answer - B | |
| 379. |
List four substances which are good absorbers of sound. |
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Answer» When sound falls on sofa, fluffs and light substances such as clothes, papers, thermocol, coating of plaster of paris, carpets, curtains, furniture, wood etc., they absorb the sound to a good extent. These are called good absorbers of sound. |
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| 380. |
Sound of frequency greater than 20 kHz is known as ……………….. A) infrasonic B) ultrasonicC) echo D) audible range |
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Answer» B) ultrasonic |
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| 381. |
The sounds heard by bat is upto ……………. A) 50 KHz B) 25 KHz C) 100 KHz D) 5 KHz |
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Answer» Correct option is C) 100 KHz |
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| 382. |
A cricket ball is seen to hit the bat first and the sound of hitting is heard a little later. Why? |
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Answer» We see the bat hitting the ball first and then hear the sound because light travels faster than the sound. |
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| 383. |
Fill in the blanks:i. Some sounds are ……………… and are heard easily.ii. Some sounds are very ……………… and cannot be heard unless we listen attentively.iii. As long as the object ……………… the sound is heard.iv. When the vibration ……………… the sound also stops.v. The intensity of sound is measured in a unit called ……………… . |
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Answer» i. loud ii. soft iii. vibrates iv. stops v. decibels(dB) |
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| 384. |
What could be the reason for better reflection of sound by rough surfaces than polished surfaces? |
Answer»
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| 385. |
One of the following can hear infrasound. This one is:A. dogB. batC. rhinocerosD. humans |
| Answer» Correct Answer - C | |
| 386. |
What do you mean by reflection of sound ? |
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Answer» Reflection of Sound— When a sound wave strikes a rigid surface, it retraces from its path is called reflection of sound. |
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| 387. |
State one use of reflection of sound. |
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Answer» The reflection of sound is used in making the speaking tube (or megaphone), sound board and trumpet. |
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| 388. |
Adjacent picture is one of application ofA) Sound B) Ultrasound C) SONAR D) All |
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Answer» Correct option is B) Ultrasound |
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| 389. |
Hertz stands for oscillations perA) second B) minuteC) hour D) milli second |
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Answer» Correct option is A)second |
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| 390. |
What is the name of very high frequency sounds which cannot be heard by the human ear? |
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Answer» Ultrasonic waves are the name of very high frequency sounds which cannot be heard by the human ear. |
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| 391. |
Sound waves travel with a speed of about `330m//s`. what is the wavelength of sound whose frequency is 550 hertz? |
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Answer» Here, Speed of waves, `v = 330 m//s` Frequency of waves, `f = 550 Hz` And, Wavelength, `lambda = ?` (To be calculated) Now, `v = f xx lambda` So, `330 = 550 xx lambda` `lambda = (330)/(550)` `lambda = 0.6m` Thus, the wavelength of sound waves is 0.6 metre. |
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| 392. |
The sound of frequency less than 20 Hertz is known as(a) Ultra sonic(b) Infra sonic(c) Sonic(d) None of these |
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Answer» (b) Infra sonic |
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| 393. |
Write the full form of dB. |
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Answer» Decibels is the full form of dB. |
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| 394. |
If 25 sound waves are produced per second, what is the frequency in hertz? |
| Answer» The frequency in hertz is equal to the number of waves produced per second. In this case, since 25 waves are being produced per second, so the frequency of the sound waves is 25 hertz (which is also written as 25 Hz). | |
| 395. |
Why do we not hear the screams of a bat? |
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Answer» We cannot hear the screams of a bat because its frequency is higher than 20,000 Hz. |
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| 396. |
Why is the light ray dancing, after sound is made in the tin? |
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Answer» The dancing of light ray, after the sound is made in the tin shows that the sound travels in the form of waves from the source of its production. |
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| 397. |
What do you infer from sound? |
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Answer» Sound is a form of energy which can travel in the form of waves through the medium. |
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| 398. |
Do you hear any sound? |
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Answer» We cannot hear any sound. |
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| 399. |
Can we say that sound is a form of mechanical energy? |
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Answer» Yes, sound is a form of mechanical energy. |
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| 400. |
Would it be possible to detect on Earth sounds produced on another planet if you had a dector sensitive enough to very low intensity sounds ? |
| Answer» No (due to absence of a material medium between the planet and the Earth). | |