You don’t use a ruler. No, you use a micrometer—the tool. It looks like a tiny C-clamp with a spinning handle that could double as a fidget toy. You place the object between the anvil and spindle, twist until it clicks, and read the number.
PPT - Microscopy PowerPoint Presentation, free download - ID:4344017
There’s also digital ones that just show you the number, because we live in the future and humans are lazy. Either way, it’s precise enough to measure the thickness of a soap bubble. Go ahead, try that with a tape measure. I dare you.
If you don’t own a micrometer, you can also use a microscope with a scale bar. But that’s less fun. And way nerdier. (No offense, microscopes. You’re still cool.)
