Capillary rise on Neutron star

CAPILLARY RISE ON SURFACE OF NEUTRON STAR

INTRODUCTION

Capillarity or capillary action is the ability of a liquid to flow in narrow spaces without the assistance of external forces. When a capillary tube is inserted into a beaker containing liquid, the level of liquid in the capillary tend to rise or fall depending on the angle of contact between liquid and the tube wall. We intend to study only the rise of liquid in a capillary tube. Since the liquid rises against gravity, the extent to which it can rise also directly depends on the local acceleration due to gravity. We thus intend to determine the extent of capillary rise by a liquid on the surface of Neutron Star.

ASSUMPTIONS

1. The local acceleration due to gravity is constant and not varying continuously

2. The angle of contact is always acute

3. The liquid is free from impurities

4. Temperature of the liquid is constant

5. The capillary tube is indestructible

6. Space time curvature does not impede capillary rise of liquid

CALCULATION

Consider a liquid [pure water] of density ‘ρ’ in a glass beaker with an inverted glass capillary tube inserted in a beaker as shown in figure.1. Let ‘r’ be the radius of the capillary tube, ‘θ’ be the angle of contact between pure water and the wall of capillary tube and ‘T’ be the surface tension of water.

Fig .1 Capillarity

The equation for capillary rise ‘h’ in the tube is given by,

h – Capillary rise in the tube (m)

T – Surface tension of water [T = 7.28*10^-2 N/m]

θ – Angle of contact between pure water and glass tube [θ = 0°]

ρ – Density of water [ρ = 1000 Kg/m³]

r – Radius of capillary tube [r = 1.5 *10^-3 m]

g – Acceleration due to gravity on Neutron Star [g = 7*10¹² m/s²]

Substituting the constants in equation (1),

The capillary rise is extremely small owing to the fact that gravitational attraction is very strong on a Neutron star. This rise may not be quantifiably meaningful.

CONCLUSION

We thus determined the capillary rise of water on the surface of Neutron Star. It is interesting to note that the capillary rise does not depend on the length of the capillary tube.