A tuning fork of frequency 250 Hz is vibrating at one end of a tube as shown in fig. (6). If maximum sound is heard at the other end, the velocity of wave will be

For maximum sound, the  path difference  Δ Should be equal to λ=v/n= v/ path difference xΔx=Vn  or  V=nΔxFrom figure. Δx=(πr−2r)=(3⋅14×1−2×1)=1⋅14so V=250×1⋅14=285m/s