MHT CET 2021 Physics Solved Paper

(c) As we know the, frequency of sound wave produced in a stretched wire is directly proportional to square root of tension in the wire
i.e., ‌‌f∝√T
Let T be the initial tension.
Therefore, for air column, fC∝√T‌‌‌⋅⋅⋅⋅⋅⋅⋅(i)
According to question, first overtone
i.e., ‌‌3fC∝√T+8‌‌‌⋅⋅⋅⋅⋅⋅⋅(ii)
From Eq. (i) and Eq. (ii), we get
‌

fC

3fC

‌‌=‌

√T

√T+8

⇒T+8‌‌=9T
⇒T‌‌=1N