22. We have two (narrow) capillary tubes

T₁ and T₂. Their lengths are l₁ and l₂ and radii of cross-section are r₁ and r₂ The rate of flow of water under a pressure difference P through tube T₁ is 8cm³/sec. If l₁ = 2l₂ and r₁ =r₂, what will be the rate of flow when the two tubes are connected in series and pressure difference across the combination is same as before (= P)

(a)  4 cm³/sec                                  (b)  (16/3) cm³/sec

(c)   (8/17) cm³/sec                         (d)  None of these

Answer-b

(14)