Q 1 – The voice box is also called as
(a) stomach
(b) heart
(c) larynx
(d) mouth
(c) larynx
Q 2 – Pitch of sound is determined by its
(a) frequency
(b) speed
(c) amplitude
(d) loudness
(a) frequency
Q 3 – Cochlea is a part of
(a) hearing organ
(b) sound producing organ
(c) muscular organ
(d) air pollution
(a) hearing organ
Q 4 – The number of vibrations made by a vibrating body in one second is
(a) frequency
(b) noise
(c) loudness
(d) pitch
(a) frequency
Q 5 – 1 hertz is equal to
(a) 1 vibration per minute
(b) 10 vibrations per minute
(c) 60 vibrations per minute
(d) 600 vibrations per minute
(c) 60 vibrations per minute
Q 6 – Voice of man is heavy compared to a woman because
(a) Female vocal cord is longer
(b) Male vocal cord is shorter
(c) Male vocal cord is longer
(d) The concept is not related
(c) Male vocal cord is longer
Q 7 – Vibration is also known as
(a) Vibratory motion
(b) Translatory motion
(c) Oscillatory motion
(d) None of these
(c) Oscillatory motion
Q 8 – Sound is produced by
(a) Non-Vibrating objects only
(b) Vibrating and non- vibrating objects
(c) Vibration has no relation to sound
(d) Vibrating objects only
(d) Vibrating objects only
Q 9 – An ultrasound equipment works at frequency
(a) Higher than 20,000 Hz
(b) Higher than 10,000 Hz
(c) Lower than 20,000 Hz
(d) Lower than 10,000 Hz
(a) Higher than 20,000 Hz
Q 10 – Match the following:
Column I | Column II |
a) Normal breathing | 98 db |
b) Soft whisper | 60 db |
c) Normal Conversation | 10 db |
d) Average factory noise | 150 db |
e) Large orchestra | 30 db |
f) Aeroplanes | 80 db |
Column I | Column II |
a) Normal breathing | 10 db |
b) Soft whisper | 30 db |
c) Normal Conversation | 60 db |
d) Average factory noise | 80 db |
e) Large orchestra | 98 db |
f) Aeroplanes | 150 db |
Q 11 – State true or false:
a) If the amplitude of vibration is large, sound is feeble.
b) Unwanted or unpleasant sound is termed as music.
c) Noise pollution may cause partial hearing impairment.
d) For human ears, the audible sound range is 20 Hz to 20,000 Hz.
e) Irregular non-periodic vibrations generally produce musical sounds.
(a) false
(b) true
(c) true
(d) true
(e) false
Q 12 –Fill in the blanks:
(a) Sound travels through _____________.
b) Above _____ db the noise becomes physically painful.
c) _____ sends vibrations to the inner ear.
d) Impairment of hearing is caused by ____ pollution.
e) The number of oscillations per second is called ________ of oscillation.
f) Birds have a ring of cartilage, called ________in their wind pipe.
g) The human ear has a special feature. This is its property of _____________.
h) The frequency of sound determines its _________ or __________.
i) The SI unit of ‘loudness’ of sound is ______.
j) Noise is derived from Latin word ________.
(a) Liquid, gas & solid
b) 80
(c) Eardrum
(d) Noise
(e) Noise
(f) Syrinx
(g) persistence
(h) shrillness or flatness.
(i) hertz
Q 13 Do all animals produce sound by vocal cords.
. No, all animals produce sound by vocal cords. For example: Bees buzz due to rapid movement of their wings.
Q 14 – Sonali heard sound of thunderbolt 5 second after she saw flash of lightning. How far is she from the place where lightning occurs? (speed of sound = 330 m/s)
Distance of Sonali from the place of lightning = 330 × 5 = 1650 m
Q 15 – A pendulum oscilliates 40 times in 4 seconds. Find its time period and frequency.
Therefore frequency = 40 vibrations /4 seconds= 10 Hertz. Time period is the time required to complete one oscillation. Frequency is the inverse of the time period. Therefore time period =110=0.1 seconds.
Q 16 – What do you mean by oscillatory motion?
The to and fro motion of an object is called vibration. This motion in both the direction from its mean position is called oscillatory motion.
Q 17 – What do you mean by time period?
The time taken by a vibrating body to complete one oscillation is called the time period.
Q 18 – Define the basic concept of sound.
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the reception of such waves and their perception by the brain.
Q 19 – What do you mean by Amplitude. Explain it.
amplitude, in physics, the maximum displacement or distance moved by a point on a vibrating body or wave measured from its equilibrium position. It is equal to one-half the length of the vibration path.
Q 20 – What is the relation between ‘time-period’ and ‘frequency’ of an oscillating body?
Time Period given by the inverse of the frequency.
Time Period = 1/frequency
Q 21 – Name one solid, one liquid and one gas through which sound can travel.
Solid: Metal (Iron, Steel, Aluminium), wood, bricks etc.
Liquid: Water Gas: Air
Q 22 – State the differences between ultrasonic sound and infrasonic sound?
Ultrasonic sound | Infrasonic sound |
(i) Sound of frequency higher than 20,000 Hz is called ultrasonic sound. | (i) Sound of frequency lower than 20 Hz is called the infrasonic sound. |
(ii) Animals like dog, bat, monkey, deer, etc., can hear ultrasonic sound. | (ii) Animals like whale, elephant, hippopotamus, giraffe, etc., can hear infrasonic sound. |
Q 23 – Differentiate between musical sound and noise.
Musical sound | Noise |
(i) Musical sound is pleasant, smooth and agreeable to the ear. | (i) Noise is unpleasant, jarring and disagreeable to the ear. |
(ii) It is produced by periodic vibrations which are regular and continuous. | (ii) It is produced by irregular vibrations which are discontinuous. |
(iii) There are no sudden changes in loudness and pitch of musical sound. | (iii) There are sudden changes in loudness and pitch of noise. |
Q 24 – What are the methods to control noise pollution?
Following are the methods to control noise pollution:
- The noise pollution can be controlled by reducing the respective sources of noise pollution.
- The blowing of horns and speaker should be strictly avoided near schools and hospitals.
- More and more trees should be planted on roadside because trees absorb sound.
Q 25 – Define frequency.
The number of oscillations completed by a vibrating body in one second is called frequency. The unit of frequency is hertz. It is denoted by Hz. If a vibrating body makes 20 oscillations in a second we say that its frequency is 20 Hz. The human voice can produce frequency between 60 Hz and 13,000 Hz. It is interesting that a human ear can hear sound of frequency between 20 Hz to 20,000 Hz.
Q 26 – How is sound produced and how is it transmitted and heard by us?
Sound is a form of energy produced and transmitted by a vibrating matter. It travels in form of waves through matter and moves in to and fro direction. When this wave reach eardrum it makes the eardrum to vibrate. The eardrum sends vibrations to the inner ear. From there, the signal goes to the brain and we are able to hear the sound.
Q 27 – What are called inaudible sounds?
The fact is that sounds of frequencies less than about 20 vibrations per second (20 Hz) and higher than about 20,000 vibrations per second (20000 Hz) cannot be detected by the human ear. Such sounds are called inaudible sounds.
Q 28 – The sound from a mosquito is produced when it vibrates its wings at an average rate of 500 vibrations per second. What is the time period of the vibration?
Time period = 1/(Frequency of Oscillation)
Frequency of oscillations = 500 Hz
Time period = 1/500 = .002 s
Q 29 – Write the loudness of the following in decibels:
Normal breathing, Soft whisper (at 5m), Normal conversation, Busy traffic and Average
factory
Normal breathing – 10 dB
Soft whisper (at 5m) – 30 dB
Normal conversation – 60 dB
Busy traffic – 70 dB
Average factory – 80 dB
Q 30 – Identify the part which vibrates to produce sound in the following
instruments: (a) Dholak (b) Sitar (c) Flute (d) Cymbals (e) Veena (f) Tabla
Dholak – stretched membrane
Sitar – strings
Flute – air columns
Cymbals – metal plates
Veena – strings
Tabla – stretched membrane
Q 37 – How does the mechanism of production of sounds in birds differ from that in human beings?
The mechanism of producing sound in birds differ from that in human beings because birds have a ring of cartilage called syrinx in their windpipe they use it in their voice Box to produce sound but in human beings there is a vocal chords or larynx which help us to produce sound.
Q 38 – Sketch larynx and explain its function in your own words.
Or
Describe how sound is produced by the human voice box (or larynx)
In humans, the sound is produced by the voice box or the larynx. It is at the upper end of the windpipe. Two vocal cords are stretched across the voice box or larynx in such a way that it leaves a narrow slit between them for the passage of air. When the lungs force air through the slit, the vocal cords vibrate, producing sound. 
Q 39 – State the various measures which can be taken to control noise pollution in our surroundings.
Measures to limit noise pollution
- Silencing devices must be installed in air craft engines, transport vehicles, industrial
machines and home appliances. - Use of automobile horns should be minimised.
- The noisy operations must be conducted away from any residential area.
- Noise producing industries should be set up away from such areas.
- TV and music systems should be run at low volumes.
Q 40 – How can you show that sound cannot travel through a vacuum?
Take a metal glass tumbler. Place a cell phone in it. Ask your friend to give a ring on this cell phone from another cell phone. Listen to the ring carefully. Now, surround the rim of the tumbler with your hands. Put your mouth on the opening between your hands.
Indicate to your friend to give a ring again. Listen to the ring while sucking air from the tumbler. You will observe that the sound become fainter as you suck. If you had been able to suck all the air in the tumbler, the sound would stop completely. Actually, sound needs a medium to travel. When air has been removed completely from a vessel, it is said that there is vacuum in the vessel. The sound cannot travel through vacuum.