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CBSE Sample Paper Class 8 Science Sound
1.) Answer the short questions
a.) How sound is produced?
b.) What is vibration?
c.) Which part tabla vibrates to produce sound?
d.) In human body where sound is produced?
e.) Where voice box is situated in our body?
f.) What is the name of membrane in our ear called?
g.) What is oscillatory motion?
h.) What is frequency?
i.) Which unit is used to describe frequency?
j.) What are the two important properties of sound?
k.) What is noise?
l.) What is musical sound?
m.) Can we hear sounds of frequencies higher than 20,000 Hz? Which animal can hear this frequency of sound?
n.) What is hearing impairment?
o.) What is noise pollution?
2.) Briefly answer the following questions
a.) Why we can’t hear sound in aempty container without air?
b.) Describe how frequency determines the pitch of sound?
c.) What is noise pollution? Give some reasons.
d.) List the harmful effects of noise pollution.
e.) How to reduce noise pollution?
3.) Fill in the blanks
a.) Sound is produced by ________ of an object.
b.) In _____ of human voice is produced.
c.) Two _______ are stretched across the voice box.
d.) Sound can’t travel through _______ .
e.) ______ is a thin stretched membrane in our ear.
f.) Vibration is also known as ________ motion.
g.) Frequency is expressed in ________ .
h.) Two important properties of sound are _______ and ________ .
i.) Noise is _______ sound.
j.) Musical instruments produce ________ sound.
4.) Write true or false
a.) Vibrating objects don’t produce sound.
b.) Vocal cords produce sound in humans.
c.) Sound can travel through vaccum.
d.) Noise is very pleasant to hear.
e.) Noise pollution is not harmful.
f.) Higher frequency causes higher pitch.
g.) Meter is used to describe frequency.
h.) Voice box is present inside of our brain.
i.) Eardrum is the membrane in our ears.
j.) Music is termed as unpleasant sound.
Answer
1.) Answer the short questions
a.) How sound is produced?
Answer – Sound is produced by vibrating objects.
b.) What is vibration?
Answer – Vibration is a movement of an object in which the object moves back and forth or to and fro, and produces sound.
c.) Which part tabla vibrates to produce sound?
Answer –The stretched membrane of tabla produces sound.
d.) In human body where sound is produced?
Answer – In human body sound is produced in the voicebox.
e.) Where voice box is situated in our body?
Answer – In our body voice box is situated in the upper end of the windpipe.
f.) What is the name of membrane in our ear called?
Answer –The name of the membrane in our ear is called eardrum.
g.) What is oscillatory motion?
Answer –Oscillatory motion is another name of vibration.
h.) What is frequency?
Answer – Frequency is described as number of oscillations per second.
i.) Which unit is used to describe frequency?
Answer – Frequency is described by the unit Hertz.
j.) What are the two important properties of sound?
Answer – Amplitude and frequency is the two important properties of sound.
k.) What is noise?
Answer – Noise is an unpleasant sound produced by different objects which causes sound pollution.
l.) What is musical sound?
Answer – The sound produced by musical instruments are called musical sound.
m.) Can we hear sounds of frequencies higher than 20,000 Hz? Which animal can hear this frequency of sound?
Answer – No, we can’t hear sounds of frequencies higher than 20,000 Hz.
Dogs can hear this frequency of sound.
n.) What is hearing impairment?
Answer – Partial or total loss of hearing due to infection, age or injury is called hearing impairment.
o.) What is noise pollution?
Answer –Presence of unwanted and excess sounds in our environment which causes harmful effects on us is called noise pollution.
2.) Briefly answer the following questions
a.) Why we can’t hear sound in a empty container without air?
Answer – Sound needs a medium to travel. This medium can be air, water or solid medium. When we suck the air out of the container, the sound can’t travel to our ears due to the lack of appropriate medium. So without an appropriate travel medium sound can’t travel.
b.) Describe how frequency determines the pitch of sound?
Answer – Frequency is the number of oscillations per second. It is one of the major properties of sound. If the frequency of vibration is higher the pitch will be higher. If the frequency of vibration is lower, the pitch will be lower also.
c.) What is noise pollution? Give some reasons.
Answer – Noise pollution is the presence of unwanted and excess sounds in our environment which causes many harmful effects on us.
Some reasons of noise pollution are,
- Bursting crackers.
- Loudspeakers.
- The sound of machines in factories.
- Sound of different vehicles.
d.) List the harmful effects of noise pollution.
Answer – The harmful effects of noise pollution includes,
- Lack of sleep.
- Hypertension.
- Anxiety.
- Partial or permanent hearing impairment.
e.) How to reduce noise pollution?
Answer –To reduce the noise pollution we can use the following steps,
- Silencing devices should be used in vehicles and factories.
- The factories and noisy operations should be placed outside residential area.
- Vehicle horn usage should be minimised.
- Trees should be planted around the road and houses to prevent sound.
3.) Fill in the blanks
a.) Sound is produced by vibration of an object.
b.) In voice box of human, voice is produced.
c.) Two vocal cords are stretched across the voice box.
d.) Sound can’t travel through vaccum.
e.) Eardrum is a thin stretched membrane in our ear.
f.) Vibration is also known as oscillatory
g.) Frequency is expressed in Hertz .
h.) Two important properties of sound are frequency and amplitude.
i.) Noise is unpleasant
j.) Musical instruments produce pleasant.
4.) Write true or false
a.) Vibrating objects don’t produce sound.
Answer – False
b.) Vocal cords produce sound in humans.
Answer – True
c.) Sound can travel through vaccum.
Answer – False
d.) Noise is very pleasant to hear.
Answer – False
e.) Noise pollution is not harmful.
Answer – False
f.) Higher frequency causes higher pitch.
Answer – True
g.) Meter is used to describe frequency.
Answer – False
h.) Voice box is present inside of our brain.
Answer – False
i.) Eardrum is the membrane in our ears.
Answer –True
j.) Music is termed as unpleasant sound.
Answer – False