Q.1 Can sound travel through- (a) iron (b) water ?
Q.2 Can sound travel through vacuum?
Q.3 Name the type of waves which are used by astronauts to communicate with one another on moon (or in outer space).
Q.4 Name one solid, one liquid and one gas through which sound can travel.
Q.5 Which of the following cannot transmit sound ?
a) Water, b) Vacuum, c) Aluminium, d) Oxygen gaS
Q.6 Name the physical quantity whose SI unit is 'Hertz'.
Q.7 What is the SI unit of frequency ?
Q.8 What type of wave is represented -
(a) by density-distance graph ?
(b) by displacement-distance graph ?.
Q.9 Is the speed of sound more in water or in steel ?.10 In which medium sound travels faster : air or iron ?
Q.11 In which medium sound travels fastest : air, water or steel ?
Q.12 Out of solids, liquids and gases :
(a) in which medium sound travels slowest ?
(b) in which medium sound travels fastest ?
Q.13 Which of the following is the speed of sound in copper and which in aluminium ?
(a) 5100 m/s
(b) 1500 m/s
(c) 3750 m/s
Q.14 If you want to hear a train approaching from far away, why is it more convenient to put the ear to the track ?
Q.15 What is the speed of sound :
(a) in air ?
(b) in water ?
(c) in iron ?
Q.16 What name is given to those aircrafts which fly at speeds greater than the speed of sound?
Q.17 What is this speed known as ?
Q.18 What is meant by supersonic speed ?
Q.19 State one observation from everyday life which shows that sound travels much more slow than light.
Q.20 Name the two types of waves which can be generated in a long flexible spring (or slinky).
Q.21 A stone is dropped on the surface of water in a pond. Name the type of waves produced.
Q.22 Name the type of waves produced when a tuning fork is struck in air.
Q.23 What is the general name of the waves consisting of :
(a) compressions and rarefactions ?
(b) crests and troughs ?
Q.24 State the general name of the waves in which the particles of the medium vibrate:
(i) in the same direction as wave.
(ii) at right angles to the direction of wave.
Q.25 What type of waves are illustrated by the movement of a rope whose one end is fixed to a pole and the other end is moved up and down ?
Q.26 What should an object do to produce sound ?
Q.27 What is the name of the strings which vibrate in our voice box when we talk ?
Q.28 Name the device which is used to produce sound in laboratory experiments fork.
Q.29 What is the nature of sound waves in air ?
Q.30 What conclusion can be obtained from the observation that when the prongs of a sound making tuning fork touch the surface of water in a beaker, the water gets splashed?
Q.31 (a) What is sound ? What type of waves are sound waves in air ?
(b) Describe an experiment to show that sound cannot pass through vacuum..
Q.32 (a) How is sound produced ? Explain with the help of an example.
(b) How does sound from a sound producing body travel through air to reach our ears ? Illustrate your answer with the help of a labelled diagram.
Q.33 (a) An electric bell is suspended by thin wires in a glass vessel and set ringing. Describe and explain what happens if the air is gradually pumped out of the glass vessel.
(b) Why cannot a sound be heard on the moon ? How do astronauts talk to one another on the surface of moon ?
Q.34 (a) Define the terms 'frequency','wavelength' and 'velocity' of a sound wave. What is the relation between them ?
(b) A body vibrating with a time-period of 1256s produces a sound wave which travels in air with a velocity of 350 m/s. Calculate the wavelength.
Q.35 (a) What are longitudinal waves and transverse waves ? Explain with the help of labelled diagrams.
(b) Give two examples each of longitudinal waves and transverse waves.
Q.36 (a) Explain the terms 'compressions' and 'rarefactions' of a wave. What type of waves consist of compressions and rarefactions ?
(b) A worker lives at a distance of 1.32 km from the factory. If the speed of sound in air be 330 m/s, how much time will the sound of factory siren take to reach the worker ?
Q.37 (a) Explain the terms 'crests' and 'troughs' of a wave ? What type of waves consist of crests and troughs?
(b) The flash of a gun is seen by a man 3 seconds before the sound is heard. Calculate the distance of the gun from the man. (Speed of sound in air is 332 m/s)..
Q.38 (a) When we put our ear to a railway line, we can hear the sound of an approaching train even when the train is far off but its sound cannot be heard through the air. Why ?
(b) How could you convince a small child that when you speak, it is not necessary for air to travel from your mouth to the ear of a listener ?
Q.39 Which of the following statement best describes frequency ?
(a) the maximum disturbance caused by a wave
(b) the number of complete vibrations per second
(c) the distance between one crest of a wave and the next one
(d) the distance travelled by a wave per second
Q.40 Which of the following vibrates when a musical note is produced by the cymbals in an orchestra ?
(a) stretched strings (b) stretched membranes
(c) metal plates (d) air columns
Q.41 If the speed of a wave is 340 m/s and its frequency is 1700 Hz, then λ for this wave in cm will be :
(a) 2 (b) 0.2 (c) 20 (d) 200
Q.42 A musical instrument is producing a continuous note. This note cannot be heard by a person having a normal hearing range. This note must then be passing through :
(a) water (b) wax
(c) vacuum (d) empty vessel