Ball pen and fountain pen depend respectively upon the principle of

The correct answer is Gravitation and surface tension.

Let us understand the working principles of both a ballpoint pen and a fountain pen step-by-step:

1. Working Principle of a Ball Pen:
A ballpoint pen has a tiny spherical ball at its writing tip. When the pen is held in a writing position (typically pointed downwards) and dragged across paper, gravity pulls the viscous ink down from the reservoir onto the ball. As the ball rolls, it transfers the ink from the reservoir onto the paper. Therefore, the primary force that feeds the ink to the tip of a ballpoint pen is gravitation.

2. Working Principle of a Fountain Pen:
A fountain pen contains a reservoir of liquid ink which is fed to the nib through a narrow channel (feed). The ink flows through this narrow channel and onto the paper due to capillary action. Capillary action is a phenomenon driven directly by surface tension and adhesive forces between the liquid ink and the solid walls of the channel. This allows the ink to flow smoothly even against gravity when writing.

Conclusion:
Thus, the ball pen and the fountain pen depend respectively upon the principles of gravitation and surface tension.