TEXTBOOK EVALUATION I. Choose the correct answer . When a sound wave travels through air, the air particles a) vibrate along the direction of the wave motion b) vibrate but not in any fixed direction c) vibrate perpendicular to the direction of the wave motion d) do not vibrate . Velocity of sound in a gaseous medium is ms – .
If the pressure is increased by times without causing a change in the temperature, the velocity of sound in the gas is a) ms – b) ms c) ms – d) ms – . The frequency, which is audible to the human ear is a) kHz b) kHz c) 15000 kHz d) 10000 kHz . The velocity of sound in air at a particular temperature is ms – . What will be its value when temperature is doubled and the pressure is halved?
a) ms – b) ms – c) × √ ms – d) / √ ms – . If a sound wave travels with a frequency of . × Hz at ms – , the wavelength will be a) . m b) .
m c) .02752 m d) . m . The sound waves are reflected from an obstacle into the same medium from which they were incident. Which of the following changes?
a) speed b) frequency c) wavelength d) none of these . Velocity of sound in the atmosphere of a planet is ms – . The minimum distance between the sources of sound and the obstacle to hear the echo, should be a) m b) m c) m d) m II. Fill up the blanks .
Rapid back and forth motion of a particle about its mean position is called . If the energy in a longitudinal wave travels from south to north, the particles of the medium would be vibrating in . A whistle giving out a sound of frequency Hz, approaches a