Reflection And Characteristics Of Sound Class-7th Goyal Brothers ICSE Physics Solutions Chapter-6 (Sound) Unit-2(Reflection And Characteristics Of Sound). We Provide Step by Step Answers of Objectives, Fill in the blanks, Match the following, True/False, Incorrect and Correct, Question Type answers of Chapter-6 (Sound) Unit-2(Reflection And Characteristics Of Sound). Visit official Website CISCE for detail information about ICSE Board Class-7.
Reflection And Characteristics Of Sound ICSE Class-7th Goyal Brothers Physics Solutions Chapter-6 Unit-2
| Board | ICSE |
| Class | 7th |
| Subject | Physics |
| Book Name | Goyal Brothers |
| Chapter-6 | Sound |
| Unit-2 |
Reflection And Characteristics Of Sound |
| Topic | Solution of exercise questions |
| Session | 2023-24 |
OBJECTIVE QUESTIONS
Reflection And Characteristics Of Sound ICSE Class-7th Goyal Brothers Physics Solutions Chapter-6 Unit-2
Que: A. Fill in the blanks spaces by choosing the correct words from the list given below:
List : depth, ultrasonic, amplitude, hertz, reflection
1. The maximum displacement of a vibrating body from its mean position is called its amplitude.
2. The SI unit of frequency is hertz.
3. Dolphins use ultrasonic sound to locate their prey.
4. The bouncing off of sound energy, on striking a hard surface, into the same medium is called reflection of sound.
5. Sonar is used to determine the depth of ocean bed.
Que: B. Statements given below are incorrect. Write the correct statements :
Question: 1. The number of vibrations of a vibrating body in one second is called its time period.
Answer: The number of vibrations of a vibrating body in one second is called frequency.
Question: 2. The sound of frequencies less than about 20 Hz is called sonic sound.
Answer: The sound of frequencies less than about 20 Hz is called infrasonic sound.
Question: 3. Reflection of sound takes place only from materials of loose texture.
Answer: Reflection of sound takes place only from materials of hard texture
Question: 4. The repetition of the sound, which is reflected from a high building, is called multiple vibrations.
Answer: The repetition of the sound, which is reflected from a high building, is called echo.
Question: 5. Pitch is the effect produced in the ear due to the sound of some particular amplitude.
Answer: Pitch is the effect produced in the ear due to the sound of some particular frequency.
Que: C. Write ‘True’ or ‘False’ for the following statements:
| Statements | True/False |
| 1. Ultrasonic wave is used for homogenizing milk. | F |
| 2. The sensation of any sound persists for 1/20 second in our ear. | F |
| 3. Loudness distinguishes a feeble sound from a loud sound of the same frequency. | T |
| 4. Pitch of the sound produced is determined by the wave nature of the vibrating body. | F |
| 5. The quality of sound is produced due to change in waveform. |
T |
Que: D. Tick (√) the most appropriate answer :
1. The time taken by a vibrating body to complete one vibration is called :
(a) wavelength
(b) frequency
(c) time period
(d) amplitude
Answer: option (c) time period is correct.
2. The frequency of infrasonic waves is :
(a) less than 20 Hz
(b) between 20 and 10,000 Hz
(c) between 20 and 20,000 Hz
(d) above 20,000 Hz
Answer: option (a) less than 20 Hz is correct.
3. Loudness of sound depends on its :
(a) frequency
(b) amplitude
(c) time period
(d) waveform
Answer: option (b) amplitude is correct.
4. Pitch is the effect produced in the ear due to sound of some particular :
(a) amplitude
(b) frequency
(c) time period
(d) waveform
Answer: option (b) frequency is correct.
5. A pure sound of single frequency is called :
(a) note
(b) tone
(c) pitch
(d) timbre
Answer: option (b) tone is correct.
Que: E. Match the statements in Column A, with those in Column B:
| Column A | Column B |
| 1. Time taken to complete one vibration. | (a) Ultrasound |
| 2. The effect produced in the ear due to sound of some particular frequency. | (b) Reflection of sound |
| 3. The bouncing off of sound from hard surface. | (c) Frequency |
| 4. Number of vibrations made by a body in one second. | (d) Pitch |
| 5. The sound of frequencies more than 20,000 Hz. |
(e) Time period |
Answer:
| Column A | Column B |
| 1. Time taken to complete one vibration. | (a) Time period |
| 2. The effect produced in the ear due to sound of some particular frequency. | (b) Pitch |
| 3. The bouncing off of sound from hard surface. | (c) Reflection of sound |
| 4. Number of vibrations made by a body in one second. | (d) Frequency |
| 5. The sound of frequencies more than 20,000 Hz. |
(e) Ultrasound |
STUDY QUESTIONS
Reflection And Characteristics Of Sound ICSE Class-7th Goyal Brothers Physics Solutions Chapter-6 Unit-2
Question: 1. (a) What is meant by amplitude?
Answer: Amplitude the maximum displacement or distance moved by a point on a vibrating body or wave measured from its equilibrium position. It is equal to one-half the length of the vibration path.
(b) Define frequency and its SI unit.
Answer: The number of periods or cycles per second is called frequency. The SI unit for frequency is the hertz (Hz). One hertz is the same as one cycle per second.
(c) Define time period and its SI unit.
Answer: The time taken by one complete oscillations in the density of the medium is called time period. It is denoted by the capital letter T. Its S.I unit is second.
Question: 2. Define the following terms :
(a) Infrasonic sound
Answer: He sound waves, having frequencies below 20Hz are called infrasonic sounds. Human beings can not hear an infrasonic sound. Animals like elephants produce rumbling sounds of low frequency (14Hz).
(b) Audible sound
Answer: The sounds having frequencies in the range of 20 Hz to 20 kHz are audible to humans. The sounds having frequencies below or above the audible sound.
(c) Ultrasonic sound
Answer: Ultrasonics sound vibrations of frequencies greater than the upper limit of the audible range for humans—that is, greater than about 20 kilohertz. The term sonic is applied to ultrasound waves of very high amplitude.
Question: 3. Name the animals that use ultrasonic sound. Explain for any one of the animals.
Answer: The ultrasonic waves are used by the bats for the finding of its food. Like bats, dolphins and the other whales also find its prey by echolocation in the water. Note: The animals and the birds that can hear the ultrasonic sounds are dogs, dolphins and the bats.
Question: 4. (a) What do you mean by reflection of sound?
Answer: When a sound wave strikes a hard surface, it changes its direction and goes back to the same medium. This phenomenon is called a reflection of sound. Laws of reflection: The angle of incidence is equal to the angle of reflection of sound.
(b) State the laws of reflection of sound.
Answer: The law of reflection of sound waves states that the angle of incidence is always equal to the angle of reflection. But unlike reflection of light on a highly smooth surface, in the reflection of the sound wave, a part of the incident wave gets transmitted to the medium where it hits.
Question: 5. (a) Define sound-proof box.
Answer: A soundproof box is a box that has been built with special materials that will block sound waves from traveling indoors or outdoors.
(b) How can you design a sound-proof box?
Answer: Find a box several inches bigger than your object on all sides. Cover the interior of the box with one layer of soundproofing material. Cut cardboard into squares about 2 inches in length and width. Cover the cardboard squares with leftover carpet (or other material).
Question: 6. Define loudness of sound. How does it depend on the amplitude of the sound?
Answer: Loudness of the sound produced by a vibrating object depends on the amplitude of vibration. If we strike a drum softly, it produces a soft sound.. Loudness is proportional to the square of the amplitude. Thus, if the amplitude is increased by three times, the loudness also increases by nine times.
Question: 7. Define pitch of sound. How does it depend on the frequency of the sound?
Answer: Pitch of the sound depends upon its frequency. As the pitch of the sound is directly proportional to frequency, Low-frequency sounds are said to have low pitch whereas sounds of high frequency are said to have the high pitch.
Question: 8. State differences between loudness and pitch of the sound.
Answer: Difference between Pitch and Loudness:- They differ on the basis of their tone quality. The pitch of a sound is our ear’s response to the frequency of sound. Whereas loudness depends on the energy of the wave. In general, the pitch is the reason behind the difference in voice quality of different individual.
Question: 9. (a) What is meant by quality of sound?
Answer: The quality of a sound is that feature that distinguishes the two sounds of equal loudness and equal pitch however emitted with the aid of using exclusive instruments. Even if the sounds of items have equal frequency and comparable wavelength, they may be exclusive.
(b) On what factor does quality of sound depend? Explain briefly.
Answer: The number of such overtones and harmonics, their relative frequencies and intensities as compared to the fundamental frequency play a role in determining the quality or richness of the sound. Therefore, in essence, it can be said that the quality of sound primarily depends upon the waveform of the sound.
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