Question

summary of the last leaf by O.Henry class 9 moments in points

Answer 1

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Answer 2

Pitch: a high pitched sound corresponds to more number of compressions and rarefactions passing a fixed point Per unit time

note
a sound of single frequency is called the tone

the sound which is produced due to a mixture of several frequency is called a note

reflection of sound
the bouncing back of sound waves in the same medium after striking a hard surface is called reflection of sound

echo
it is the repetition of sound due to reflection of sound waves back towards the source

reverberation
the multiple reflection of sound from the walls, ceilings, floor of a hall is called reverberation


answer the following

what is sound and how is it produced ?
.............. sound is the form of energy which produces a sensation of hearing in our ears it is produced due to vibrations of a body



describe with the help of the diagram how compressions and rarefactions are produced in our nearest source of sound
............. sound in air gets propagated in the form of longitudinal waves consisting of region of compressions and rarefactions
............. consider a tuning fort in the state of vibration.as a prong moves towards right it compresses the layer of air in contact with it as a has elasticity the compressed air tends to relieve itself of its try and moves towards to the right to compress the next layer and so on. thus a wave of compression move towards the right at the point of compression there is a increase of pressure and shown in the form of crest. at the point of rarefaction the concentration particles is least and has been shown in trough.
.......... when the prong moves towards left a region of reduced pressure or rarefaction is produced towards right there in the next layer bring at Higher pressure moves towards the left to equalise the reduced pressure producing another rarefaction region to its right and so on. in this way a series of compressions and rarefactions move in forward direction these compressions and rarefactions finally reached the eardrum of the observer and we hear sound.

.. ...... ......... C..... R.... C
prong---->|||||||||-|-|-|-|||||||||||

...................... R...... C...... R
prong <----|-|-|-|-|||||||||||-|-|-|-|



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