Physics (CBSE 9) Sound - Work Sheet

Benjamin Academia 1 Physics Work Sheet Grade 9 Chapter 12 -Sound ( CBSE ) Q1. Fill in appropriate words in the blanks in the following statement : Sound is a form of …………. which produces a sensation of ……………… in our ears. Q2. A tuning fork has two ……… and a ……. . Q3. Sound is produced by human beings by vibrations in the. Q4. A bee produces the buzzing sound by ………………… in its wings. Q5. A complete to and fro motion of a body is known as one …………………….. . Q6. The SI unit of measuring frequency is known as …………… . Q7. A bee makes about three hundred vibrations by one of its wings in two seconds. The frequency of vibrations of the wing is …………….. . Q8. A compression is a region of ………………. pressure and a region of low pressure is known as …………………….. . Q9. A sound wave is a ……………….. wave. Q10. Any sound wave is produced by ………………………. in a body. Benjamin Academia 2 Q11 Sound waves can travel through …………………. , …………………………. as well as …………. Q12. Sound waves need a ……………… to travel through and cannot travel through ……………….. . Q13. The sound wave in air is ………………………… ( longitudinal /transverse ). Q14. The air particles (molecules) vibrate …………………… the direction of motion of the longitudinal sound waves in air. Q15. Light waves are …………………………………. (mechanical /electromagnetic). Light waves do not require a …………………. to travel through. Light waves are ………………….. ( longitudinal /transverse ). Q16. In a concert hall you are alone and watching a musician playing violin. Describe in detail how you hear the sound of violin. Q17. The distance between two consecutive compressions or rarefactions is termed as ……………………….. Q18 A sea diver sees that two successive crests pass by him in an interval of 2 s. The distance between two successive crests is 4 m. What is the speed of the sea wave ? Q19. Soft sound has ……………… amplitude and loud sound has ……………….. amplitude. Q20. The ……………… or ……………………… of sound is that characterstic which enables us to distinguish one sound from another having the same ……………. and ………………….. . Q21. A tone is sound of ……………………. frequency. Benjamin Academia 3 Q22. A note is sound of mixture of several ………………….. . Q23. The characterstic that determines loudness of a sound wave is ……………………and ……………….. determines pitch of a note. Q24. Frequency and wavelength of a sound wave at room temperature are respectively 500 Hz and 0.68 m. What is the wavelength of another wave that has frequency 200 Hz ? Q25. A source of sound emits a tone of frequency 800 Hz. What is the time interval between two successive rarefactions at a point in the medium. What is the time interval between two successive compressions at the point ? Q26. The amount of the sound energy passing per second through unit area is called the ………………. of sound. Q27. Distinguish between loudness and intensity of a sound wave. Q28. The speed of sound in air at 0 °C is 331 m/s . The speed of sound at 20 °C would be ……………… (more /less ) than 331 m/s. Q29. The speed of sound is largest in …………………………. (iron, distilled water, oxygen). Q30. The human brain registers a sound for a duration of ………………. s (0.1 , 0.01, 0.001). Q31. A shepherd stands 510 m away from a hill and shouts to gather the herd of goats. He heard echo of his voice after 3 s. What is the speed of sound ? Benjamin Academia 4 Q32. Why are the ceilings of the concert halls curved ? Q33. A wave of frequency 25 KHz is …………………………. (ultrasound /infrasound ). Q34 A ship sends an ultrasonic wave to measure the depth of the sea bed. The signal returns to the ship in 3.4 s. If the speed of the ultrasonic waves in water is 1400 m /s , calculate the depth of the sea. For one to one lessons, contact : sc.benjamin@yahoo.com