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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.
| 951. |
The audible range of frequency is 20 Hz to 20,000 Hz. Determine the corresponding range of time periods of vibrations. |
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Answer» `f_(1) = 20 H_(z)` `T_(1) = 1/20 s = 5 xx 10^(-2) s.` `f_(2) = 20,000 Hz` From `T_(2) = (1)/(20,000) s = 5 xx 10^(-5) s.` Range is `5 xx 10^(-2) s` to `5 xx 10^(-5) s.` |
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| 952. |
Say True or False with explanation:If the amplitude of vibration is large, sound is feeble. |
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Answer» False. When the amplitude of vibration of a sound is large, the sound is very loud. The sound is feeble, when the amplitude is small. Loudness of a sound is proportional to the square of the amplitude of its vibration. |
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| 953. |
The audible range of a human ear is 20 Hz to 20 kHz. Convert this into corresponding wavelength range. The speed of sound at ordinary temperature is `340 m//s`. |
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Answer» Here, speed of sound in air, `v = 340 m//s` lowest frequency, `v_1 = 20 Hz` highest frequency, `v_2 = 20 kHz = 20 xx 10^2 Hz` Clearly, upper limit of wavelength, i.e., `lamda_1 = (v)/(v_1) = (340)/(20) = 17 m` and lower limit of wavelength, i.e., `lamda_2 = (v)/(v_2) = (340)/(20 xx 10^3) = 0.017 m` Thus, the audible wavelength range is 0.017 m to 17 m. |
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| 954. |
Say True or False with explanation:For human ears, the audible range is 2 Hz to 20,000 Hz. |
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Answer» True. Human being can hear sounds only within the range of 20-20,000 Hz. We cannot hear the sound having frequency out of this range. |
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| 955. |
Mark the correct choice as:(a) Both assertion and reason are true and reason is the correct explanation of assertion. (b) Both assertion and reason are true but reason is not the correct explanation of assertion. (c) Assertion is true but reason is false. (d) Assertion is false but reason is true. (e) Both Assertion and reason are falseAssertion: Trees should be planted along the road to control noise pollution. Reason: Trees act as noise buffers. |
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Answer» (a) Both assertion and reason are true and reason is the correct explanation of assertion. |
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| 956. |
Pick out the odd one and give reason:Trumpet, Flute, Saxophone, Mouthorgan. |
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Answer» Mouthorgan. Reason: Mouthorgan is a reed instrument whereas the others are wind instruments. |
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| 957. |
Mark the correct choice as:(a) Both assertion and reason are true and reason is the correct explanation of assertion. (b) Both assertion and reason are true but reason is not the correct explanation of assertion. (c) Assertion is true but reason is false. (d) Assertion is false but reason is true. (e) Both Assertion and reason are falseAssertion: Women have shriller sound than men. Reason: Men produced higher frequency sound than women. |
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Answer» (c) Assertion is true but reason is false Reason: Women produce higher frequency sound than men. |
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| 958. |
Fill in the blanks: 1. ……… is produced when an object is set to vibrate. 2. The substance through which sound is transmitted is called ………… 3. Sound cannot travel in ………4. The speed of sound is ……… in solids than in liquids.5. ……… is the distance between two consecutive particles, which are in the same phase of vibration.6. ……… is the number of vibrations of a particle in the medium in one second. 7. In any medium, as the ……… increases, the speed of sound also increases. 8. The speed of sound in air is 331 ms at ……… and ……… at 22°C. 9. The unit of frequency is ……… 10. The amount of water vapour in the air is known as ………… |
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Answer» 1. Sound 2. medium 3. vacuum 4. more 5. Wavelength 6. Frequency 7. temperature 8. 0°C, 344 ms-1 9. hertz 10. humidity |
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| 959. |
Match the following:1. Audible range(a) 50 Hz to 45000 Hz2. Infrasonic range(b) Above 20.000 Hz3. Ultrasonic range(c) 20 Hz to 20 k Hz4. Dog’s hearing range– (d) Below 20 Hz |
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Answer» 1. c 2. d 3. b 4. a |
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| 960. |
Take the tray of an empty match box and stretch a rubber band around it, along its length. Then, pluck the stretched rubber band with your index finger. What do you observe? Do you hear any sound? |
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Answer» Observation: 1. On plucking the rubber band, it starts vibrating. 2. We can hear a feeble humming sound as long as the rubber band is vibrating. 3. The humming sound stops as soon as the rubber band stops vibrating. Conclusion: This confirms that sound is produced by vibrating bodies. |
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| 961. |
Do the frequency of sound produced by Men and Women are same? |
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Answer» No, the frequency of sound produced by men and women are different. |
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| 962. |
A sound has a frequency of 60 Hz and a wavelength of 20 m. What is the speed of the sound? |
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Answer» Given: Frequency n = 60 Hz Wavelength λ = 20 m To find: Speed V = ? Formula: V = n λ V = 20 x 60 V = 120 ms-1 |
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| 963. |
What is meant by audible sound? |
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Answer» Sound with the frequency ranging from 20 Hz to 20,000 Hz is called sonic sound or audible sound. |
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| 964. |
What are the symptoms of hearing loss? |
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Answer» 1. Ear ache. 2. A feeling of fullness or fluid in the air. 3. Ringing in your ears. |
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| 965. |
Many animals move the ear flap (or pinna) in order to focus their hearing in a certain direction. Can human do so ? |
| Answer» No , humans canot move the ear flap. However, they can cup their hand around the ear and by rotating the hand can achieve the similar result to some extent. | |
| 966. |
Name the sound producing organ in human. |
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Answer» Voice box or Larynx. |
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| 967. |
The hearing range of human ear is ………….. (a) 20 Hz to 20 kHz (b) less than 20 Hz (c) more than 20 k Hz(d) none |
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Answer» (a) 20 Hz to 20 kHz |
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| 968. |
The outer part of human ear is called(a) Pinna(b) Eardrum(c) Tympanum(d) None of these |
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Answer» The outer part of human ear is called Pinna. |
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| 969. |
Fill in the blanks.Main source of sound in human is …………The sound waves having frequency more than 20,000 hertz are called …………The international unit of frequency is ……………The loudness of sound depends on ……………The pitch of sound depends on …………….. |
Answer»
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| 970. |
Explain loudness or intensity of sound. |
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Answer» Loudness is the characteristic of a sound which distingushes a feeble sound from a loud sound of the some frequency. When the amplitude of a vibrating body increases loudness increases. We can also say that when surface area of the vibrating bodies increases loudness increases. |
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| 971. |
How do we feel sound? |
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Answer» Sound produces vibration in eardrum. It send to brain through ear cavity by which we feel sound. |
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| 972. |
To locate its prey in the darkness the owl or the bat emits: (a) infrasonic waves (b) ultrasonic waves (c) sonic waves (d) infrared waves |
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Answer» (b) ultrasonic waves. |
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| 973. |
What happens to frequency if the amplitude is changed? |
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Answer» The frequency remains the same even if the amplitude is increased or decreased. |
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| 974. |
Differentiate infrasonic sounds and ultrasonic sounds. |
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Answer» Infrasonic sound is the sound with frequency lower than 20Hz but ultrasonic sound is the sound with frequency higher than 20000Hz or 20 kHz. |
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| 975. |
What is infrasonic sound? |
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Answer» A sound with a frequency less than 20Hz is called infrasonic sound. |
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| 976. |
Define Reverberation. |
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Answer» A sound created in a big hall will persist by repeated reflection from the walls until it is reduced to a value where it is no longer audible. The repeated reflection that results in this persistence of sound is called reverberation. |
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| 977. |
1. Name the type of waves which are used for sound ranging. 2. Why are these sound waves mentioned in (i) above are not audible to us? 3. Give one use of sound ranging. |
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Answer» 1. Ultrasonic waves. 2. Because their frequency lies beyond the limits of audibility (20Hz—20,000Hz). 3. To locate the position of the object under water and to find the depth of sea. |
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| 978. |
Which characteristic of sound will change, if there is a change in 1. its amplitude 2. its waveform. |
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Answer» 1. With the change in amplitude, the loudness of sound changes. 2. With the change in waveform the quality of sound changes. |
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| 979. |
What do you understand by free vibrations of a body? Give one example. |
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Answer» The vibrations of a body in the absence of any external force on it are called the free vibrations. Eg.: When we strike the keys of a piano, various strings are set into vibration at their natural frequencies. |
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| 980. |
For a particular string (given material and radius), what are the factors on which its frequency of vibration depends? |
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Answer» For a particular string (given material and radius), the frequency of vibration of the string depends upon its vibrating length and the tension in the string. [Note: in the above case, frequency is proportional to the square root of the tension and inversely proportional to the length.] |
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| 981. |
What is meant by vibration? |
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Answer» Vibration of an object is necessary for the production of sound. As long as the object vibrates, the sound is heard. When the vibration stops, the sound also stops. |
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| 982. |
1. Name one factor which affects the frequency of sound emitted due to vibrations in an air column. 2. Name the unit used for measuring the sound level. |
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Answer» 1. The length of vibrating air column affects its frequency. More the length of vibrating air column, lesser is its frequency. 2. Decibel (dB) is the unit used for measuring sound level. |
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| 983. |
State one way of increasing the frequency of a note produced by an air column. |
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Answer» The frequency of the note produced in the air column can be increased by decreasing the length of the air column. |
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| 984. |
What is meant by the natural frequency of vibration of a body? On What factors does it depend? |
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Answer» When each body capable of vibrating is set to vibrate freely and it vibrates with a frequency f. It is the natural frequency of vibration of the body. The natural frequency of vibration of a body depends on the shape and size of the body. |
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| 985. |
A type of electromagnetic wave has wavelength 50A. 1. Name the wave. 2. What is the speed of this wave in vacuum? 3. State one use of this type of wave. |
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Answer» 1. X-Ray. 2. 3 x 108m/s. 3. X-Ray are used for detection of fracture in bones. |
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| 986. |
Name one factors on which the frequency of sound emitted due to vibrations in an air column depends. |
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Answer» The frequency of sound emitted due to vibration in an air column depends on the length of the air column. |
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| 987. |
State one condition for a body to execute free vibrations. |
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Answer» The free vibrations of a body occur only in vacuum because the presence of medium offer some resistance due to which the amplitude of the vibration does not remain constant, but it continuously decreases. |
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| 988. |
A blade made 3000 vibrations in 10 seconds. Then the frequency of the blade is ………….. vibr. / sec. A) 30 B) 300 C) 3000 D) 30000 |
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Answer» Correct option is B) 300 |
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| 989. |
A blade, fixed at one end, is made to vibrate by pressing its other end and then releasing it. State one way in which the frequency of vibrations of the blade can be lowered. |
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Answer» The frequency of vibrations of the blade can be lowered by increasing the length of the blade or by sticking a small weight on the blade at its free end. |
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| 990. |
The velocity of sound in air, in water and in a given solid is, `330 ms^(-1), 1350 ms^(-1)` and `1500 ms^(-1)`, respectively. If a vibrating tuning fork of frequency 150 Hz is placed in each of these media, then find the distance covered by the sound in air, water and solid, respectively, at the end of 50 vibrations. |
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Answer» Speed of sound in air `= 330 ms^(-1)`. Speed of sound in water `= 1350 ms^(-1)`. Speed of sound in solid `1500 ms^(-1)`. Frequency of turning fork, (n) = 150 Hz. i.e., it performs 150 vibrations in 1 second. `therefore` The time taken by the tuning fork to complete 50 vibrations `= 1/3 s`. The distance travelled by sound in three media in 1 second is 330 m, 1350 m, 1500 m. `therefore` The distance covered by sound in the three given media in 1/3 s is `330 xx 1/3 = 110 m` in air. `1350 xx 1/3 = 450 m` in water. `1500 xx 1/3 = 500 m` in solid. |
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| 991. |
The more is the energy spent to set a body into vibration,A. the louder is the sound produced.B. the intensity (loudness) of sound produced by vibrating body always remains constant.C. the softer is the sound produced.D. the amount of energy spent and loudness are not related to each other. |
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Answer» Correct Answer - A The loudness of sound increases with increase in amplitude or energy and vice versa. |
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| 992. |
Chanukya was eager to know the time taken by sound to travel the same distance in water and air. So, he set a body on vibration with a frequency of 250 Hz in air and the sound produced bu this is heard at a distance of 175 m. Now if the body is vibrated in water, what is the difference in the time taken by the sound to travel the same distance in water and air ? (The velocity of sound in air and water is `350 ms^(-1)` and `1400 ms^(-1)`, respectively). |
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Answer» (i) Frequency of body, (n) = 250 Hz. Distance, (d) = 175 m. Speed (velocity) of sound (V) `= 350 ms^(-1)`. `therefore` Time taken by the sound to travel 175 m in air `= ("distance")/("speed") = (175 m)/(350 ms^(-1)) = 1/2 s.` (ii) When it is vibrated in water, the number of vibrations completed in 1 second (i.e., frequency) is the same `therefore` n = 250 Hz. Distance, (d) = 175 m Speed of sound in water `(v) = 1400 ms^(-1)`. `therefore` Time taken by sound to travel 175 m in water (t). `= (175 m)/(1400 ms^(-1)) = 1//8 s` `therefore` Time difference `= (1/2 - 1/8)s` `= (1/2 - 1/8)s = (4/8 - 1/8)s = 3/8s`. |
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| 993. |
If more energy is spent to set a body into vibration, thenA. the amplitude of vibrating body is more.B. the amplitude of vibrating body is less.C. the amplitude of vibrating body always ramains same even after setting it into vibration.D. Both (b) and (c). |
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Answer» Correct Answer - A The more is the energy spent or set the body into vibration, the more is the amplitude of the vibration. |
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| 994. |
The instruments made of long and hollow pipes with a certain number of holes on the sides areA. wind or reed instruments.B. stringed instruments.C. drum instruments.D. All the above |
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Answer» Correct Answer - A Wind or reed instruments are made of long and hollow pipes with a certain number of holes on the sides. |
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| 995. |
Which of the following statements is wrong ?A. Galton Whistle produces frequency more than 20,000 Hz.B. Infrasonic vibrations are used for homogenizing milk.C. Dolphins use ultrasonic sound to locate their prey.D. None of the above |
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Answer» Correct Answer - B Ultrasonic vibrations are used for homogenizing milk. |
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| 996. |
How does the medium affect the amplitude of free vibrations of a body? |
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Answer» The presence of the medium offers some resistance to motion, so the vibrating body continuously loses energy due to which the amplitude of the vibration continuously decreases. |
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| 997. |
A bucket kept under a running tap is getting filled with water. A person sitting at a distance is able to get an idea when the bucket is about to be filled. 1. What changes take place in the sound to give this idea? 2. What causes the change in the sound? |
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Answer» 1. The sharp pitched sound slowly changes to low pitched sound as the bucket gets filled. The sound almost dies when the bucket is completely filled. 2. As the length of vibrating air column decreases due to the water, the frequency of the sound changes. |
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| 998. |
The time taken to displace a vibrating body from its mean position to maximum displacement is ________A. time periodB. `("time period")/(2)`C. 2 time periodD. `("time period")/(4)` |
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Answer» Correct Answer - D The time in which a vibrating body completes one vibration is called time period. So, the time taken by a vibrating body to displace form its mean position to maximum displacement is `= ("time period")/(4)` |
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| 999. |
The maximum possible displacement of a vibrating body from its mean position during its motion is equal toA. its amplitudeB. half its amplitudeC. twice its amplitudeD. its frequency |
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Answer» Correct Answer - A The maximum displacement of a vibrating body from its mean position is called amplitude. |
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| 1000. |
What are damped vibrations? How do they differ from free vibrations? Give one example of each. |
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Answer» The periodic vibrations of a body of decreasing amplitude in the presence of resistive force are called the damped vibrations. The amplitude of the free vibrations remains constant and vibrations continue forever. But, the amplitude of damped vibrations decreases with time and ultimately the vibrations ceases. For eg, When a slim branch of a tree is pulled and then released, it makes damped vibrations. A tuning fork vibrating in air excute damped vibrations. |
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