NCERT Exemplar Solutions Class 9 Science Solutions for Sound - Exercise in Chapter 12 - Sound

Question 19 Sound - Exercise

Establish the relationship between speed of sound, its wavelength and frequency. If velocity of sound in air is 340 m s–1, calculate

(i) wavelength when frequency is 256 Hz.

(ii) frequency when wavelength is 0.85 m


Relationship between Sound speed, wavelength and frequency

Speed = π·π‘–π‘ π‘‘π‘Žπ‘›π‘π‘’/ π‘‡π‘–π‘šπ‘’

V = π‘Šπ‘Žπ‘£π‘’π‘™π‘’π‘›π‘”π‘‘β„Ž/ π‘‡π‘–π‘šπ‘’

V = wavelength Γ— 1/timeπ‘Šπ‘Žπ‘£π‘’π‘™π‘’π‘›π‘”π‘‘β„Žπ‘₯1 π‘‘π‘–π‘šπ‘’

Frequency = 1/ π‘‘π‘–π‘šπ‘’

V = wavelength Γ— frequency

(1) Wavelength = 𝑠𝑝𝑒𝑒𝑑/ π‘“π‘Ÿπ‘’π‘žπ‘’π‘’π‘›π‘π‘¦

= 340/ 256

= 1.32 mType equation here.

(2) Frequency = speed / wavelength

= 340/ 0.85

= 400 HZ

Video transcript
"hello everyone welcome to leader learning i'm good preet your science tutor today's question is establish the relationship between speed of sound and its wavelength and frequency if the velocity of sound in air is 340 meter per second calculate wavelength when frequencies 256 hertz and second frequency when wavelength is 0.85 meters so let's start our answer since speed of sound that is v is equals to distance upon time that is lambda upon t here lambda is wavelength right now from here we can say that v is equals to lambda into 1 by t and we know that nu that is frequency is equals to 1 upon t fine so from this we can write v as lambda into nu that is frequency so this is a relation between speed of sound wavelength and frequency this is speed wavelength and frequency now we have to calculate the wavelength when frequency is 256 hertz so for the first we can calculate lambda is equals to speed upon nu that is frequency that will be 340 upon 250 6 which is equals to 1.33 meters now in the second part we have to calculate frequency that is new will be equals to speed upon lambda that is wavelength so here will be 340 and the value of lambda is 0.85 so we will get the answer as 400 hertz these are the required answers for more such videos please subscribe leader learning and for any doubts drop a comment thank you"
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