Science - Grade 8 (C ...

Q1. Fill in the blanks.

                          i.        Time taken by an object to complete one oscillation is called ___________.

                         ii.        Loudness is determined by the __________ of vibration.

                        iii.        The unit of frequency is _____________.

                        iv.        Unwanted sound is called ____________.

                         v.        Shrillness of a sound is determined by the ____________ of vibration.

                        vi.        Higher the ____________ of vibration, the higher is the __________, and shriller is the sound.

          vii.        Sound which is pleasing to the ear is called _____________ sound.

 

Q2. State True (T) or False (F).

                           i.        Sound cannot travel in vacuum. _____

                          ii.        The number of oscillations per second of a vibrating object is called its time period. _____

                         iii.        If the amplitude of vibration is large, sound is feeble. _____

                         iv.        For human ears, the audible range is 20 Hz to 20,000 Hz. _____

                          v.        The lower the frequency of vibration, the higher is the pitch. _____

                        vi.        Unwanted or unpleasant sound is termed as music. _____

          vii.        Noise pollution may cause partial hearing impairment. _____

 

Q3. Name one animal which can hear ultrasonic sounds.

 

Q4. How is sound produced?

 

Q5. How does an object produce sound?

 

Q6. Name the sound producing organ in humans.

 

Q7. Name the organs of hearing in our body.

 

Q8. Name that part of ear which vibrates when outside sound falls on it.

 

Q9. Name the unit used to measure the loudness of sound.

 

Q10. Name the quantity whose unit is 'hertz'.

 

Q11. Does any part of the body vibrate when we speak? Name the part.

 

Q12. On what factor does the pitch of a sound depend?

 

Q13. What is the name of passage in outer ear which carries sound waves to the eardrum?

 

Q14. Choose the correct answer: Sound can travel through

(a) gases only      (b) solids only

(c) liquids only     (d) solids, liquids and gases.

 

Q15. Which of the following voices is likely to have minimum frequency?

(a) Baby girl        (b) Baby boy

(c) A man           (d) A woman

 

Q16. What is frequency of oscillation?

 

Q17. What is the audible range of frequencies for human ears?

 

Q18. What is vibration?

 

Q19. How does a sound producing object differ from silent?

 

Q20. What brings the sound of a ringing telephone bell to our ears?