{"id":25850,"date":"2021-06-24T13:56:21","date_gmt":"2021-06-24T08:26:21","guid":{"rendered":"https:\/\/ncertsolutions.guru\/?p=25850"},"modified":"2021-06-24T13:56:21","modified_gmt":"2021-06-24T08:26:21","slug":"ncert-solutions-for-class-8-science-chapter-13","status":"publish","type":"post","link":"https:\/\/ncertsolutions.guru\/ncert-solutions-for-class-8-science-chapter-13\/","title":{"rendered":"NCERT Solutions for Class 8 Science Chapter 13 Sound"},"content":{"rendered":"

These NCERT Solutions for Class 8 Science<\/a> Chapter 13 Sound Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.<\/p>\n

Sound NCERT Solutions for Class 8 Science Chapter 13<\/h2>\n

Class 8 Science Chapter 13 Sound Textbook Exercise Questions and Answers<\/h3>\n

Page 168-169<\/span><\/p>\n

Question 1.
\nSound can travel through
\na. gases only
\nb. solids only
\nc. liquids only
\nd. solids, liquids and gases
\nAnswer:
\nd. solids, liquids and gases<\/p>\n

Question 2.
\nVoice of which of the following is likely to have minimum frequency?
\na. Baby girl
\nb. Baby boy
\nc. A man
\nd. A woman
\nAnswer:
\nc. A man<\/p>\n

Question 3.
\nIn the following statements, tick \u2018T\u2019 against those which are true, and \u2018F\u2019 against those which are false:
\na. Sound cannot travel in vacuum. (T\/F)
\nb. The number of oscillations per second of a vibrating object is called its time period. (T\/F)
\nc. If the amplitude of vibration is large, sound is feeble. (T\/F)
\nd. For human ears, the audible range is 20 Hz to 20,000 Hz. (T\/F)
\ne. The lower the frequency of vibration, the higher is the pitch. (T\/F)
\nf. Unwanted or unpleasant sound is termed as music. (T\/F)
\ng. Noise pollution may cause partial hearing impairment. (T\/F)
\nAnswer:
\na. True
\nb. False
\nc. False
\nd. True
\ne. False
\nf. False
\ng. True<\/p>\n

Question 4.
\nFill in the blanks with suitable words,
\na. Time taken by an object to complete one oscillation is called ………………
\nb. Loudness is determined by the ……………… of vibration.
\nc. The unit of frequency is ………………
\nd. Unwanted sound is called ………………
\ne. Shrillness of a sound is determined by the ……………… of vibration.
\nAnswer:
\na. time period,
\nb. amplitude,
\nc. hertz,
\nd. noise,
\ne. frequency<\/p>\n

\"NCERT<\/p>\n

Question 5.
\nA pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
\nAnswer:
\nNumber of oscillations = 40
\nTotal time taken = 4 seconds
\nTime period = Time taken for one oscillation
\n= \\(\\frac{\\text { Total time }}{\\text { Total number of oscillations }}\\)
\n= \\(\\frac{4 \\text { seconds }}{40}\\) = \\(\\frac {1}{10}\\)second = 0.1 second
\nFrequency of oscillations is defined as the number of oscillations of a vibrating body per second.
\nFrequency = \\(\\frac{\\text { Number of oscillations }}{\\text { Total time }}\\) = \\(\\frac {40}{4}\\) = 10 Hz.<\/p>\n

Question 6.
\nThe 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?
\nAnswer:
\nThe time required to complete on oscillation is known as time period. It is given by the inverse of the frequency.
\nTime period = \\(\\frac{1}{\\text { Frequency of oscillations }}\\)
\nFrequency of oscillations = 500 Hz
\nTime period = \\(\\frac {1}{500}\\) = 0.002 s<\/p>\n

Question 7.
\nIdentify the part which vibrates to produce sound in the following instruments:
\na. Dholak
\nb. Sitar
\nc. Flute
\nAnswer:
\na. Stretched membrane,
\nb. String,
\nc. Air column<\/p>\n

Question 8.
\nWhat is the difference between noise and music? Can music become noise sometimes?
\nAnswer:
\nUnwanted sound that is unpleasant to ear is called noise. A pleasant sound is called music. Music can become noise at many instances. When someone tries to enjoy very loud music, it can become noise for someone else. When loud music is played during religious celebrations or marriages, it can be annoying for many people.<\/p>\n

Question 9.
\nList sources of noise pollution in your surroundings.
\nAnswer:
\nSome sources of noise pollution are as follows:<\/p>\n