Two capillary tubes of same length each of 50 cm but of different radii 4 mm and 2 mm are connected in series. When water flows, the pressure difference between the ends of the arrangement is P . Then the pressure difference between the ends of the first tube is

Step-by-step solution

The figure below represents the capillary tubes of same lengths but different radii. From the Poiseuille's equation, the expression for the water resistance, R = 8 η l π r 4 R ∝ 1 r 4 The ratio of water resistance in tube I and II, R l R I I = r I I 4 r l 4 = 16 × 10 - 12 16 × 16 × 10 - 12 16 R I = R I I Let R I = R , R I I = 16 R Thus, the pressure difference between ends of first tube is, p R + 16 R × R = p 17