CBSE Class 8 Science Sound Worksheet Set B

CBSE Class 8 Science Worksheet - Sound Part B. Revision worksheets, Sample papers, Question banks and easy to learn study notes for all classes and subjects based on CBSE and CCE guidelines. Students and parents can download free a collection of all study material issued by various best schools in India. The study material has been carefully compiled by the best teachers in India. The students should practice the questions database to get better marks in examination. Please refer to other links for free download of high quality study material. Based on CBSE and CCE guidelines. Based on the same pattern as released by CBSE every year. Study material for final/ term/ SA1/ SA2 Examinations conducted by various schools affiliated to Central Board of Secondary Education (CBSE) in India and abroad. CBSE Study material has been compiled to help students preparation which will helps the students to concentrate more in areas which carry more marks.

Question. Voice of which of the following is likely to have minimum frequency?
(a) Baby girl
(b) Baby boy
(c) A man 
(d) A woman
Answer: C

Question. Choose the correct answer. Sound can travel through
(a) gases only
(b) solids only
(c) liquids only
(d) solids, liquids and gases 
Answer: D 

True and False: 

Question. If the amplitude of vibration is large, sound is feeble. 
Answer: False

Question. Unwanted or unpleasant sound is termed as music. 
Answer:  False

Question. For human ears, the audible range is 20 Hz to 20,000 Hz. 
Answer: True

Question. Sound cannot travel in vacuum. 
Answer: True

Question. The number of oscillations per second of a vibrating object is called its time period.
Answer: False

Question. Noise pollution may cause partial hearing impairment. 
Answer: True

Question. The lower the frequency of vibration, the higher is the pitch. 
Answer: False

Fill in the blanks: 

Question. The unit of frequency is _____.
Answer:  Hertz.

Question. Shrillness of a sound is determined by the _____ of vibration
Answer: Frequency

Question. Time taken by an object to complete one oscillation is called _____.
Answer: Time period

Question. Unwanted sound is called _____.
Answer: Noise

Question. Loudness is determined by the _____ of vibration.
Answer: Amplitude

Question and Answers: 

Question. Identify the part which vibrates to produce sound in the following instruments.
(a) Dholak
(b) Sitar
(c) Flute
Answer: (a) Dholak - Stretched membrane.
(b) Sitar - Stretched string.
(c) Flute - Air column.

Question. Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away from the roadside. Which house would you suggest your parents should buy? Explain your answer.
Answer: I would suggest my parents to buy the house which is three lanes away from the roadside. This would protect us from noise pollution which is maximum at roadside building.

Question. What is the difference between noise and music? Can music become noise sometimes?
Answer: The type of sound which is unpleasant to listen is known as noise whereas music is a pleasant sound, which produces a sensation.
Yes, music can become noise when it’s too loud.

Question. A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
Answer: Number of oscillations in 4 seconds = 40
Number of oscillations in 1 seconds = 40/4 = 10
Therefore, frequency of pendulum = f = 10 Hz
Now Time period = 1/f = 1/10 = 0.1 sec.

Question. Explain in what way noise pollution is harmful to humans.
Answer: Noise pollution causes: (a) Lack of sleep, (b) Anxiety, (c) Hypertension.

Question. Sketch larynx and explain its function in your own words.
Answer: The other name of larynx is voice box. It is present at the upper end of the windpipe. The function of larynx is to produce sound with the help of two vocal cords on passing air. 

Question. 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?
Answer: Number of vibrations in 1 seconds = 500
Therefore, frequency of vibration = f = 500 Hz
Now Time period = 1/f = 1/500 = 0.002 sec.

Question.. Lightning and thunder take place in the sky at the same time and at the same distance from us. Lightning is seen earlier and thunder is heard later. Can you explain why?
Answer: Speed of the light is much more than the speed of sound. Thus, lightning is seen earlier than thunder.

Question. List the sources of noise pollution in your surroundings.
Answer: Noise pollution sources are:
(a) Bus and car horns.
(b) Firecrackers and loudspeakers.
(c) High volumes in televisions and DJ etc.
(d) Sound of kitchen appliances.
(e) Sirens from factories

Please refer to attached file for CBSE Class 8 Science Worksheet - Sound Part B