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PHYSICS [2 Mark Question Answer]

Sound · ICSE STD 8 (ICSE - English Medium). 7 questions.

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[2 Mark Question Answer]

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7 questions · timed · auto-graded

Question 12 Marks
What do you understand by the terms pitch, timbre and loudness of a sound ?
Answer
Pitch : The characteristic of sound that differentiates a shrill sound from a hoarse sound is called pitch.
Timbre : Timbre distinguishes two notes of the same pitch $($or frequency$)$ and loudness $($or amplitude$)$ produced by different bodies.
Loudness : Loudness is a characteristic of sound which distinguishes a feeble sound from a loud one of the same frequency.
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Question 22 Marks
Define amplitude, time period and frequency with respect to a sound wave. State the relationship between time period and frequency of a wave.
Answer
The maximum displacement of a wave on either side of its mean position is known as its amplitude. Frequency of a wave is the number of oscillations completed by it in one second. Time period of a wave is the time taken by it to complete one oscillation. The time period and frequency of a sound wave are related by the expression
$f = 1/T$
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Question 32 Marks
A monotone is unable to deliver the message imparted by the orator. Give reason.
Answer
If an orator speaks in a monotone, he won’t be changing the pitch,;volume, rhythm, timbre and speed of his voice, For instance, he won’t make his voice assertive while asking a question, stress words to add emphasis, pause to add suspense, vary his voice to express different emotions. So, he won’t be able to deliver his message.
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Question 42 Marks
Loudness of a sound depends on its amplitude. Give reason.
Answer
Loudness of a sound depends on its amplitude. Higher the amplitude, louder is the sound. As the amplitude of a wave is directly related to the energy it carries, we can say that greater the energy carried by a wave, louder is the sound produced.
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Question 52 Marks
Why is it advised not to use earphones at loud volumes?
Answer
It is advised not to use earphones at loud volumes because sounds above $80\  dB$ can cause many health hazards, some of which are listed below.
$1.$ Feeling of annoyances aggression, anxiety and stress.
$2.$ High blood pressure heart problems.
$3.$ Headache, feeling of fatigue, sleep disturbances.
$4.$ Reduced work efficiency.
$5.$ Loss of hearing.
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Question 62 Marks
If a key of a piano is first struck gently and then much harder, how will the loudness and pitch of the sound change?
Answer
In a piano, musical sound is produced by pressing different keys. When a key is pressed, it causes a hammer to strike a string of a particular length and thickness and produces a sound of a particular frequency. Each key produces a sound of a particular frequency. So, pressing a key gently or harder doesn’t change the pitch of the sound. However, hitting a key harder causes the hammer attached to it strike the string more harder, hence, increasing the loudness of the sound.
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Question 72 Marks
Why does the pitch of the sound increases when a nail is hammered into a wall ?
Answer
As a nail is hammered into a wall, its length keeps on decreasing. We know that the pitch of a sound is inversely proportional to the length of the vibrating body. So, the pitch of the sound increases as the length of the nail hammered into the wall decreases.
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[2 Mark Question Answer] - PHYSICS STD 8 Questions - Vidyadip