Waves

JEE Main level, numerical answer, medium

96 of 142

Question 96 of 142

A closed organ pipe of length LL and an open organ pipe contain gases of densities ρ1{\rho }_{1} and ρ2{\rho }_{2} respectively. The compressibility of gases are equal in both the pipes. Both the pipes are vibrating in their first overtone with same frequency. The length of the open pipe is x3Lρ1ρ2\dfrac{x}{3}L\sqrt{\dfrac{{\rho }_{1}}{{\rho }_{2}}}, where xx is _______.
(Round off to the Nearest Integer)

Show answer and solution

Answer: 4


fc=f0{f}_{c}={f}_{0}
3VC4L=2V02L′\dfrac{3{V}_{C}}{4L}=\dfrac{2{V}_{0}}{2{L}^{'}}
3VC4L=V0L′\dfrac{3{V}_{C}}{4L}=\dfrac{{V}_{0}}{{L}^{'}}
L′=4L3V0VC=4L3B.ρ1ρ2.B{L}^{'}=\dfrac{4L}{3}\dfrac{{V}_{0}}{{V}_{C}}=\dfrac{4L}{3}\sqrt{\dfrac{B.{\rho }_{1}}{{\rho }_{2}.B}} (BB is bulk modulus)
=4L3ρ1ρ2=\dfrac{4L}{3}\sqrt{\dfrac{{\rho }_{1}}{{\rho }_{2}}}
x=4x=4

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