Why pen can ink flow out?
When you use a pen to write letters on paper, the ink immediately appears. You must have wondered: why when you write, ink in pens will constantly flow out; When you stop writing, the ink doesn’t flow anymore? Let’s do an experiment: Plug a small glass tube into a glass beaker containing water, the water quickly rises up inside the tube,
then we see the water surface in the tube is higher than the water in the glass cup. The phenomenon is called capillary phenomena. The fountain pen is designed to apply this capillary principle. It relies on a series of capillary grooves on the body of the pen and the small opening at the tip of the pen that transports the ink from the inside of the pen to the tip of the pen. When writing the words, the tip of the pen just touches the paper, the ink immediately adheres to the paper, leaving on it the sharp strokes.
When I stopped writing, why did the ink in the fountain pen not flow? Let us do another small experiment to make this clear.
Grab a cardboard cover over the top of the glass filled with water, squeeze the cover tightly, and quickly flip the whole glass and cover upside down, then gently remove the cover. The cardboard board is then sucked into the top of the glass and caught the full amount of water in the cup. What is the strength that supports the cover so that the water in the glass does not flow out? That is the effect of atmospheric pressure. It is the atmospheric pressure that supports the cover and water in the cup. When not writing, the ink in the pen does not flow out because of that, because the atmospheric pressure outside the pen is larger than the internal pressure, so it can be kept.
Keywords: Fountain pen; Capillary phenomenon; Atmospheric pressure.