b. If both the assertion and the reason are true but the reason is not the correct explanation of the assertion. c. Assertion is true, but the reason is false.
d. Assertion is false, but the reason is true. ) Assertion: The change in air pressure affects the speed of sound. Reason: The speed of sound in a gas is proportional to the square of the pressure ) Assertion: Sound travels faster in solids than in gases.
Reason: Solid posses a greater density than that of gases. VI. Answer very briefly . What is a longitudinal wave?
. What is the audible range of frequency? . What is the minimum distance needed for an echo?
. What will be the frequency sound having . m as its wavelength, when it travels with a speed of ms – ? .
Name three animals, which can hear ultrasonic vibrations. VII. Answer briefly . Why does sound travel faster on a rainy day than on a dry day?
. Why does an empty vessel produce more sound than a filled one? . Air temperature in the Rajasthan desert can reach °C.
What is the velocity of sound in air at that temperature? (V = ms – ) . Explain why, the ceilings of concert halls are curved. .
Mention two cases in which there is no Doppler effect in sound? VIII. Problem Corner . A sound wave has a frequency of Hz and a speed of ms – in a medium.
Find the wavelength of the sound wave. . The thunder of cloud is heard . seconds later than the flash of lightning.
If the speed of sound in air is ms – , what will be the height of the cloud? . A person who is sitting at a distance of m from a source of sound is listening to a sound of Hz. Find the time period between successive compressions from the source?
. An ultrasonic wave is sent from a ship towards the bottom of the sea. It is found that the