Physics ICSE Class 7 Important Questions Chapter 6 Sound
Additional Questions
A. Tick (S) the following questions.
Question 1.
Sound is a form of energy which we can –
(a) see
(b) feel
(c) hear
(d) none of these
Answe:
(c) hear
Question 2.
Sound can be –
(a) noise
(b) music
(c) both (a) and (b)
(d) none of these
Answer:
(c) sboth (a) and (b)
Question 3.
Sound travels like a –
(a) ray
(b) wave
(c) both (a) and (b)
(d) none of these
Answer:
(b) wave
Question 4.
Audio means –
(a) sound
(b) picture
(c) both (a) and (b)
(d) none of these
Answer:
(a) sound
Question 5.
Different animals can hear –
(a) same type of sound
(b) different types of sound
(c) both (a) and (b)
(d) none of these
Answer:
(b) different types of sound
Question 6.
Our voice is produced with the help of –
(a) voice box
(b) larynx
(c) both (a) and (b)
(d) none of these
Answer:
(c) both (a) and (b)
Question 7.
Like light sound is –
(a) reflected
(b) not reflected
(c) sometimes (a) sometimes (b)
(d) none of these
Answer:
(a) reflected
Question 8.
Videos mean –
(a) having sound
(b) having pictures
(c) both (a) and (b)
(d) none of these
Answer:
(b) having pictures
Question 9.
We can identify different sounds made by different musical instruments from the –
(a) quality of sounds
(b) loudness of sound
(c) both (a) and (b)
(d) none of these
Answer:
(a) quality of sounds
Question 10.
When the teacher says in class please do not make noise, then the sound is –
(a) pleasant
(b) irritating
(c) both (a) and (b)
(d) none of these
Answer:
(b) irritating
B. Answer the following questions.
Question 1.
To identify different sources of sound.
Answer:
Sound is produced by natural and man made sources.
A. Natural sources : These are the sound producing sources , belonging to living and non-living family which are not created artificially.
These are mainly of three types :
(a) Earth sound (geophony) sources
(b) Animal sound (biophony) sources
(c) Human sound (anthrophony) sources
B. Man made sources : These sources are artificial sources.
They are mainly :
(a) Transport
(b) Industry
(c) Music
Question 2.
Describe sound as a longitudinal wave.
Answer:
Particles in air surrounding a vibrating object start vibrating about their mean positions. They further disturb nearby particles and make them vibrate by giving them energy. This process keeps on repeating. Vibrations of particles are in the direction of travel of sound so sound wave is a longitudinal wave.
Question 3.
Define amplitude and frequency of sound.
Answer:
Amplitude: It is the greatest displacement of vibration of the vibrating particle producing a sound wave from its mean position. It is denoted by A.
Frequency : It is an important term of sound wave. Number of cycles per second gives the frequency of a sound wave. It is denoted by n, f or u (neu).
Question 4.
List examples of Reflection and Absorption of sound.
Answer:
Applications of reflection of sound : There are many applications of reflection of sound. Some of them are given below:
(a) Stethoscope
(b) Loud speaker
(c) Sound board
(d) Echo system
Absorption of sound :
(a) Furniture kept in a hall is an example of single absorber.
(b) Materials like stone wood are porous absorbers.
Question 6.
Analyse the Relative speed of sound in different mediums.
Answer:
To demonstrate absorption of sound.
Material required : Empty container, rubber bands of different sizes, hand towels.
Procedure :
- Stretch rubber bands and place them on the container as shown in the figure.
- Disturb the rubber bands and note the sound.
- Place hand towel in the container. Note the change in sound.
- Put more hand towels in the container. Note the change in sound.
Question 7.
Design a sound-proof box.
Answer:
Material required : A big card board box, egg carton, thermocol sheet, foam, scissors, knife, gum, cellotape, alarm clock or mobile phone.
Procedure :
- Cut egg carton, thermocol sheet and foam into 6 pieces each according to the size of the cardboard box.
- Paste layers of foam, thermocol and egg carton on all walls of the cardboard box.
- Put the alarm clock or mobile phone in the box with its alarm on.
- Seal the box with the six layers cover with cellotape.
Result : It is observed that sound of alarm is loud when it is kept outside the box. This sound reduces a lot when the alarm clock or mobile phone is kept inside the box with lid open. The sound is almost not heard when the box is properly covered from all sides and top.
C. Tick (✓) the best choice :
Quesrtion 1.
Sound is a form of energy that gives sense of –
(a) speaking
(b) hearing
(c) touch
(d) none of these
Answer:
(b) hearing
Quetion 2.
The box which helps us in producing sound is called –
(a) voice box
(b) larynx
(c) ear
(d) (a) or (b)
Answer:
(d) (a) or (b)
Question 3.
The commonly used door bell is a –
(a) mechanical device
(b) chemical device
(c) optical device
(d) electric device
Answer:
(d) electric device
Question 4.
Biophony sources are related to –
(a) shouting sounds
(b) earth sounds
(c) animal sounds
(d) human sounds
Answer:
(c) animal sounds
Question 5.
Sound is –
(a) a pressure wave
(b) a pure compression wave
(c) a pure rarefaction wave
(d) not a wave
Answer:
(a) a pressure wave
D. Fill in the blanks :
Question 6.
Our ears can hear sounds of frequency …………… Hz to Hz.
Answer:
Our ears can hear sounds of frequency 20 Hz to 20,000 Hz.
Question 7.
bodies produce sound.
Answer:
Vibrating bodies produce sound.
Question 8.
Sound is a (longitudinal/transverse) wave.
Answer:
Sound is a longitudinal wave.
Question 9.
………….. of a string of a musical instrument produce music.
Answer:
Vibrations of a string of a musical instrument produce music.
Question 10.
Voice of a girl is ………… than that of a boy.
Answer:
Voice of a girl is shriller than that of a boy.
E. True and false :
Question 11.
Amplitude is the greatest displacement of a vibration.
Answer:
True.
Question 12.
Loudness depends upon amplitude of sound wave.
Answer:
True.
Question 13.
Number of cycles per second gives the frequency of a sound wave.
Answer:
True.
Question 14.
Pitch has nothing to do with sound.
Answer:
False.
Question 15.
Sound does not need a medium to propagate.
Answer:
False.
F. Define the following :
Question 16.
Sound
Answer:
Sound is a form of energy that gives sensation of hearing.
Question 17.
Pitch
Answer:
It is a characteristic of sound wave which depends upon frequency of the sound wave.
Question 18.
Frequency
Answer:
Number of cycles per second gives the frequency of a sound wave. It is denoted by n, f or o (neu).
Question 19.
Wave length
Answer:
It is the length from one compression to the next compression or from one rarefaction to the next rarefaction. It is denoted
by Roman letter lambda x
Question 20.
Time period
Answer:
It is the time taken to complete one vibration of the vibrating object producing sound. It is denoted by T.
ICSE Class 7 Physics Important Questions