Why does a smell reach you before you can see where it came from?
Picture this: someone opens a bag of crisps at the other end of a bus, and within seconds you can smell it , even though nothing visibly moved through the air toward you. That's diffusion at work, and it's happening constantly around you, whether you notice it or not.
Diffusion: When particles are packed more densely in one region than another, their constant random movement naturally causes them to scatter outward until they're spread evenly , that process of net movement from a crowded zone to a less crowded one is called diffusion.
The key word is net , individual particles are bouncing around in every direction at once, but the overall drift goes from high concentration to low. Think of it like a group chat where one person is spamming messages and everyone else gradually mutes or leaves , the messages (particles) spread out until the chaos is evenly distributed.
Imagine your school cafeteria at the start of lunch: everyone piles through one door and clusters near the entrance. Over time, without anyone directing them, people drift toward the emptier corners of the room. Nobody decided to spread out , it just happens because there's more space available elsewhere. That's exactly what diffusing particles do.
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