{"id":3665,"date":"2023-01-04T06:53:29","date_gmt":"2023-01-04T06:53:29","guid":{"rendered":"https:\/\/theexampillar.com\/ncert\/?p=3665"},"modified":"2023-01-31T07:00:50","modified_gmt":"2023-01-31T07:00:50","slug":"ncert-solutions-class-8-science-chapter-13-sound","status":"publish","type":"post","link":"https:\/\/theexampillar.com\/ncert\/ncert-solutions-class-8-science-chapter-13-sound\/","title":{"rendered":"NCERT Solutions Class 8 Science Chapter 13 Sound"},"content":{"rendered":"

NCERT Solutions Class 8 Science\u00a0<\/span><\/h2>\n

The NCERT Solutions in English Language for Class 8 Science Chapter – 13 (Sound) <\/strong>has been provided here to help the students in solving the questions from this exercise.<\/span><\/p>\n

Chapter – 13 (Sound)<\/span><\/h2>\n

1. Choose the correct answer.
\n<\/strong>Sound can travel through
\n<\/strong>(a) gases only
\n(b) solids only
\n(c) liquids only
\n(d) solids, liquids and gases
\nAnswer –\u00a0 <\/strong>(d) solids, liquids and gases<\/span><\/p>\n

2. Voice of which of the following is likely to have a minimum frequency?
\n<\/strong>(a) Baby girl
\n(b) Baby boy
\n(c) A man
\n(d) A woman
\nAnswer –\u00a0 <\/strong>(c) A man<\/span><\/p>\n

3. In the following statements, tick \u2018T\u2019 against those which are true and \u2018F\u2019 against those which are false.
\n<\/strong>(a)<\/strong> Sound cannot travel in a vacuum. (T\/F)
\n(b)<\/strong> The number of oscillations per second of a vibrating object is called its time period. (T\/F)
\n(c)<\/strong> If the amplitude of the vibration is large, the sound is feeble. (T\/F)
\n(d)<\/strong> For human ears, the audible range is 20 Hz to 20,000 Hz. (T\/F)
\n(e)<\/strong> The lower the frequency of vibration, the higher the pitch. (T\/F)
\n(f)<\/strong> Unwanted or unpleasant sound is termed as music. (T\/F)
\n(g)<\/strong> Noise pollution may cause partial hearing impairment. (T\/F)<\/span><\/p>\n

Answer – <\/strong><\/span><\/p>\n

(a)<\/strong> Sound cannot travel in a vacuum. (True)<\/strong>
\n(b)<\/strong> The number of oscillations per second of a vibrating object is called its time period. (False)<\/strong>
\n(c)<\/strong> If the amplitude of the vibration is large, the sound is feeble. (False)<\/strong>
\n(d)<\/strong> For human ears, the audible range is 20 Hz to 20,000 Hz. (True)<\/strong>
\n(e)<\/strong> The lower the frequency of vibration, the higher the pitch. (False)<\/strong>
\n(f)<\/strong> Unwanted or unpleasant sound is termed as music. (False)<\/strong>
\n(g)<\/strong> Noise pollution may cause partial hearing impairment. (True)<\/strong><\/span><\/p>\n

4. Fill in the blanks with suitable words.
\n<\/strong>(a)<\/strong> Time taken by an object to complete one oscillation is called __________.
\n(b)<\/strong> Loudness is determined by the __________ of vibration.
\n(c)<\/strong> The unit of frequency is __________
\n(d)<\/strong> Unwanted sound is called __________.
\n(e)<\/strong> The shrillness of a sound is determined by the __________ of vibration.<\/span><\/p>\n

Answer –
\n<\/strong>(a)<\/strong> Time taken by an object to complete one oscillation is called the\u00a0time period<\/strong><\/span>.
\n(b)<\/strong> Loudness is determined by the\u00a0amplitude<\/strong><\/span>\u00a0of vibration.
\n(c)<\/strong> The unit of frequency is hertz<\/span><\/strong>.
\n(d)<\/strong> Unwanted sound is called noise<\/strong><\/span>.
\n(e)<\/strong> The shrillness of a sound is determined by the\u00a0frequency<\/strong><\/span>\u00a0of vibration.<\/span><\/p>\n

5. A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
\n<\/strong>Answer –\u00a0<\/strong>Time period is defined as the time required to complete one oscillation.
\nFrequency is defined as the number of oscillations per unit time.
\nTime = 4 sec.
\nTime Period = (Time taken) \/ (Number of Oscillations)
\nTime Period = \"\\frac{4}{40}\"\u00a0 = 0.1 sec.
\nFrequency = (Number of Oscillations)\/ (Time taken)
\nFrequency = \"\\frac{40}{4}\" = 10Hz.<\/span><\/p>\n

6. The sound from a mosquito is produced when it vibrates its wings at an average rate of 500 vibrations per second. What is the time period of the vibration?
\n<\/strong>Answer –\u00a0<\/strong>Frequency = 500 vibrations\/second.
\nTime Period = (Time Taken)\/ (Number of Oscillations)
\n= \"\\frac{1}{500}\" = 0.002 sec.
\n<\/span><\/p>\n

7. Identify the part which vibrates to produce sound in the following instruments.
\n<\/strong>(a)<\/strong> Dholak
\n(b)<\/strong> Sitar
\n(c)<\/strong> Flute<\/span><\/p>\n

Answer –
\n<\/strong>(a) Dholak \u2013<\/strong> Dholak has stretched membranes that vibrate to produce sound.<\/span><\/p>\n

(b) Sitar<\/strong> \u2013 In sitar, the stretched strings, when vibrate, they produce sound.<\/span><\/p>\n

(c) Flute \u2013<\/strong> In flute, the air column inside it vibrates and produces sound.<\/span><\/p>\n

8. What is the difference between noise and music? Can music become noise sometimes?
\n<\/strong>Answer –\u00a0<\/strong><\/span><\/p>\n\n\n\n\n\n\n
Noise<\/strong><\/span><\/td>\nMusic<\/strong><\/span><\/td>\n<\/tr>\n
Sounds which are not pleasant to hear is called Noise<\/span><\/td>\nSounds which are pleasant to hear is called Music<\/span><\/td>\n<\/tr>\n
We do not like such sounds<\/span><\/td>\nWe like such sounds<\/span><\/td>\n<\/tr>\n
Example –\u00a0 <\/strong>Sounds produced by musical instruments like guitar, piano<\/span><\/td>\nExample –\u00a0<\/strong>Sounds of Vehicles,\u00a0Bursting of Crackers<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

9. List sources of noise pollution in your surroundings.
\n<\/strong>Answer –\u00a0<\/strong>Noise pollution sources in ou surroundings are listed below:<\/span><\/p>\n