Q.

Two open organ pipes of lengths 60 cm and 90 cm resonate at 6th and 5th harmonics respectively. The difference of frequencies for the given modes is ____ Hz

(Velocity of sound in air = 333 m/s)            [2024]


Ans.

(740)

For first open organ pipe

f=nv2lf6=6v2l1

f6=6v2(0.6)=5v                 ...(i)

For second open organ pipe

f5=5v2(l2)=5v2(0.9)=259v               ...(ii)

Δf=f6-f5=5v-25v9

Δf=(45-25)v9=209v=209×333Δf=740 Hz