Ncert – class 8- science – Chapter 10: Sound 1 Welcome to your Ncert - class 8- science - Chapter 10: Sound 1 1. Some whistles are designed to produce waves that can attract the attention of dogs but humans do not notice these waves. What kind of waves are these? These are normal sounds waves whose frequency is less than 20 � 20 Hz. Humans cannot hear them because these waves have frequencies below the audible range. These are supersonic sound waves. These are electromagnetic waves. These are normal sounds waves whose frequency is more than 20,000 Hz. Humans cannot hear them because these waves have frequencies above the audible range None 2. The voice box is called: Larynx Stomach Heart Mouth None 3. In sound wave: Direction of vibration of particle is same as direction of energy Direction of vibration of particle is perpendicular to the direction of energy None of these Vibration of particles does not exist None 4. A metallic spoon falls on a metal plate making a huge sound and upon bouncing from the plate, it falls on to the pile of sand below it with no noise being heard. Sound is not heard on sand because Sound is absorbed by sand particles Sand does not vibrate Sound generated by the plate is more than the sand particles Vibration of metal plate is more than sand particles None 5. Vibrating part of flute is Rubber band String Air-column Stretched membrane None 6. Which characteristic of the sound helps you to identify your friend by his voice while sitting with others in a dark room? The frequency of the sound. The pitch of the sound. The speed of the sound. The wavelength of the sound. None 7. The hearing range of human ear is 20 Hz to 20,000 Hz Less than20 Hz More than 20,000 Hz 20 Hz to 25,000 Hz None 8. Which of the following can caused by noise pollution? Hypertension All of the above Anxiety Lack of sleep None 9. Which of the following factor influence speed of sound most? Nature of medium Source of sound Humidity Temperature None 10. .......... is the number of vibrations of a body in one second. Compression Frequency Pitch Time-period None 11. Large amplitude of sound vibrations will produce: Shreak Meak sound Slow sound Loud sound None 12. When a tightly stretched band is plucked it Vibrate but do not produce sound Produce sound but do not vibrate Vibrate and produce sound Only oscillate to and fro None 13. Low sound such as normal breathing has loudness up to 20 -30 decibel 50 - 60 decibel 5 decibel 10 decibel None 14. Eardrum is a part of Hearing organ Sound producing organ Reproductive organ Skeletal system None 15. In most of the cases vibration of objects are not visible because Frequency is very less Amplitude is very small Wavelength is very small Wavelength is very large None 16. An empty vessel produces louder sound than a filled one because. The density of air is less than the density of liquid contained in the vessel when filled The air molecules in empty vessel have greater amplitude and hence greater intensity than liquid molecules in the filled vessel The liquid in the filled vessel absorbs the vibrations of the liquid molecules The kinetic energy of particles constituting the air column is greater as compared to the kinetic energy of particles of liquid column None 17. The sound in the audible range is called Ultra sonic Sonic Light sound Sub sonic None 18. Statement 1: Loudness is the characteristic of a musical sound by which a loud sound can be distinguished from a faint sound.Statement 2: Echo is always produced when sound is incident on the hard and polished surface. Both statements 1 and 2 are true and statement 2 is the correct explanation of statement 1. Statement 1 is false but statement 2 is true Both statements 1 and 2 are true but statement 2 is not the correct explanation of statement 1. Statement 1 is true but statement 2 is false None 19. The siren of an ambulance needs to be a loud and piercing sound. Therefore, its main characteristics should be: high pitch and large amplitude high pitch and small amplitude low pitch and small amplitude low pitch and large amplitude None 20. Which of the following require material medium for propagation? Sound Light Transverse wave All of these None Time's up Please Share This Share this content Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Leave a Reply Cancel replyCommentEnter your name or username to commentEnter your email address to commentEnter your website URL (optional) Save my name, email, and website in this browser for the next time I comment.
