1.Pens are designed for writing, while screwdrivers are designed for turning screws. This fundamental difference in purpose dictates their design and functionality. Pens have a smooth, pointed tip and contain ink that flows easily onto paper, allowing for controlled and continuous lines. Screwdrivers, on the other hand, have a flattened or specialized tip designed to engage with screw heads, providing torque for turning.
2.1. Friction
Writing materials like pencil (graphite) or pen (ink) need friction between their tip and the surface.
Paper is rough, so it provides enough friction for graphite particles (from pencil) or ink (from pen) to stick.
A smooth plate has very little friction, so the pencil tip just slides without leaving marks.
2. Absorption
Paper is porous (it has tiny holes and fibers) that can absorb ink from a pen and hold graphite powder from a pencil.
A plate is non-porous and smooth, so ink or graphite cannot enter or stick properly—it just smears or wipes away.