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When a stretched wire and a tuning fork are sounded together Y beats Per second are produced When length of wire is  90  cm or 100 cm frequency of the fork is 195 Hz  Then Y = ?
 

Option: 1

9.75


Option: 2

11.42


Option: 3

8.26


Option: 4

7.25


Answers (1)

best_answer

Wire of length  90 cm            frequency = n1

wire of length  100 cm           frequency  = n2

 n_1-n=Y\rightarrow (1)\,\,eq

n-n_2 =Y\rightarrow (2)\,\,eq

(1) and (2) eq add

n_1-n_2=2\,Y\rightarrow (3) \,\,eq

\frac{n_1}{n_2}=\frac{l_2}{l_1}=\frac{100}{90} \\

n_1=195 \\

\frac{195}{n_2}=\frac{100}{90}

100 \,n_2 =195 \times 90 \\

n_2 =\frac{195 \times 90}{100} \\

n_2 =\frac{39 \times 9}{2} \\

n_2 =\frac{351}{2}=175.5 \\

n_2 =175.5

n_1 \,\,and\,\,n_2
put the value of eq (3)

n_1-n_2=2 Y \\

195-175.5=2 Y\\

19.5=2 Y \\

Y=\frac{19.5}{2}=\frac{195}{20} \\

Y=9.75 \\

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Sayak

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