Maharashtra Board Class 8 Science Solution Chapter 15 – Sound
Balbharati Maharashtra Board Class 8 Science Solution Chapter 15: Sound. Marathi or English Medium Students of Class 8 get here Sound full Exercise Solution.
Std |
Maharashtra Class 8 |
Subject |
General Science Solution |
Chapter |
Sound |
(1) (a) The region in a sound wave, with higher pressure and density called compression and that with low pressure and density is called rarefaction.
(b) Medium is necessary of generation of sound.
(c) The total number of empress ions and rarefactions produced per second in a sound have is 1000. The frequency of the sound wave is 1000HZ.
(d) Different sounds notes have different frequencies of sound waves.
(e) In loud speaker, electric energy is converted into sound wave energy.
(2) (a) We produce sound by larynx . As the vocal cords are stretched across the larynx it leave a narrow slit between them and sound is produced.
When lungs force air through the site the vocal cord vibrate. Muscles that are attracted to the cords can make the cords tight or loose. When the vocal cords are tight and thin, the sound notes from our larynx are different.
(b) We know sound generation and propagation needs a medium. As there are no air or no any medium exist in moon, So the Astronauts cannot hear each other directly on moon.
(c) Propagates of sounds vibrates the atmospheric condition, that is the air molecules get motion due to sound. As the sound generations and propagation just need a medium to vibrate, not the medium to get move, so the air is not required to move from one place to other.
(3) The string based instrument like guitar, we get different note of generation, as the frequency of vibrations of the string is changed by changing the tension on the string or changing the vibrating length of the string.
And the air blowing instrument like flute, the holes on the flute are opened or closed to changed the length of vibrating air column. So the frequency of waves changed and different sound notes are formed.
(4) Sound is produced in larynx. When the lungs force air through the slit, the vocal cords vibrate. Muscles attached to the vocals cords make the cords tight or thin. When the air came from lungs through the vocal cords, the sound generated.
(6) Human larynx – Vibrations in vocal cords.
Loudspeaker – Vibrations of screen.
Jal-tarang – Vibrations in air column.
Tuning fork – Vibrations of metal arms.
Sitar – Vibrations in strings.