Page no. 236
Chapter: Sound
Very Short questions
1.
What is sound? Name any two sources of sound.
Sound is a form of energy that gives the sensation of hearing. Two sources
of sound are guitar and bell.
2.
How is sound produced?
Sound is produced by the vibration of an object.
3.
What is the speed of sound in air?
The speed of sound in air is 332 m/s.
4.
Which of the following affects the speed of
sound: temperature, humidity or altitude?
All three factors affect the speed of sound, but temperature has the
greatest effect.
5.
What is an echo?
An echo is the repetition of a sound caused by reflection of sound from a
distant surface.
6.
Give an example of a natural source of sound.
An example of a natural source of sound is running water.
7.
What is the frequency of sound wave?
The number of vibrations made by a vibrating body in one second is called
frequency.
8.
Which material is the best conductor of
sound?
Diamond is the best conductor of sound.
9.
What is the propagation of sound wave?
The propagation of sound wave is the process by which sound travels from
its source to our ears.
10. What
is the speed of sound in water?
The speed of sound in water is 1500 m/s.
Short questions
1.
Not necessary
2.
Name the different types of sound that we
hear in our daily life.
The different types of sound that we hear in our daily life are:
i) Pleasant sound (e.g. flowing water, chirping of the bird, sound from musical
instrument, etc.)
ii) Unpleasant sound (e.g. loud sound coming from factories, horns, etc.)
3.
How does sound travel through air?
When an object vibrates, it moves back and forth quickly and pushes
neighboring air particles. These particles start vibrating and bump into the
particles next to them, passing the energy along in waves. When these
vibrations reach our ears, our eardrums vibrate, and our brain interprets them
as sound.
4.
Compare the speed of sound in air, water
and solids.
Sound travels at different speeds in different media. Generally, it travels
slowest in gases, faster in liquids, and fastest in solids. For example, its
speed is about 332 m/s in air, 1500 m/s in water, and 5200 m/s in steel.
5.
What factors can affect the speed of
sound in a medium?
The factors that affect the speed of sound in a medium are temperature,
density and elasticity.
6.
What is the speed of sound in sound in
steel medium?
The speed of sound in steel medium is 5200 m/s.
7.
The speed of sound is more in liquid
medium and less in a gas medium, why?
Particles in a liquid are packed much closer together than particles in a
gas. This closeness allows vibrating particles to bump into each other and pass
along energy much faster. In gases, particles are far apart, so energy transfer
takes longer.
8.
How does humidity in the air affect the
propagation of sound?
When humidity increases, the amount of water vapor (moisture) in the air
increases. Moisture makes the air particles move faster, so sound travels
slightly faster through humid air than dry air.
9.
What is the unit used to measure
frequency? How does sound travel through a vacuum?
The unit used to measure frequency is Hertz (Hz). Sound cannot travel
through a vacuum because it needs a material medium to propagate.
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