AP EAMCET Engineering 21 Apr 2019 Shift 2 Paper

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=‌

8ηl

πr4

R∝‌

1

r4

The ratio of water resistance in tube I and II,
‌

RI

RII

=‌

(rII)4

(rI)4

=‌

16×10−12

16×16×10−12

16RI=RII
Let RI=R,RII=16R
Thus, the pressure difference between ends of first tube is,
‌

p

R+16R

×R=‌

p

17