The length of two open organ pipes are l and l+ΔlΔl<<l, if u is the speed of sound, find the frequency of beats between them
vΔl3l2
vΔl4l2
vΔl8l2
vΔl2l2
Beat frequency =f1−f2 =v2l−v2l+Δl =v2l1−1+Δll−1 =v2l1−1+Δll=vΔl2l2