I know that black light (UV) is often used to see the microbes (colloquially referred to as germs) on people's hands but is there any way by which we can examine the microbes on people's hands without having the surroundings be completely dark (what is required for black light to work) or using a microscope? I am trying to show a roomful of people the microbes on my hand but the surroundings aren't going to be completely dark and there is no way I can use a microscope.

  • $\begingroup$ The term germ is generally not used in biology as it is poorly defined. In general, it is defined as a microorganism, which would mean that by definition you can't see them with your bare eyes. I don't think a black light would be of any help though. You can detect specific disease with a black light but I don't think it would help you see individual germs (as they are too small by definition, at least if you want to define a germ as being a microorganism). What make you think a black light would help? $\endgroup$ – Remi.b Jan 11 at 6:46
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    $\begingroup$ A germ is typically defined as a pathogenic agent. Is there any reason you want to find something that is pathogenic? Or maybe, you just meant that you would like to see a microorganism? $\endgroup$ – Remi.b Jan 11 at 6:46
  • $\begingroup$ I understand germs isn't the best use of vocabulary. I meant microorganisms/bacteria. The answer about the agar plates works perfectly but now if I kill the microorganisms in a roomful of people, how can I show that the microorganisms are killed in front of them? $\endgroup$ – aadityak_968 Jan 12 at 6:01
  • $\begingroup$ @aadityak_968 You should move your comment to the answer. You are commenting on the answer, not the question. $\endgroup$ – WYSIWYG Jan 23 at 11:41

Given your constraints, the only solution available would require some amount of preparation. If you are so inclined, you can purchase sterile, ready-to-use agar plates online, which you can then inoculate with microorganisms from your hands by simply touching the agar surface with your palms, and letting the plates incubate at room temperature. A day or two's time should be sufficient for plenty of microorganisms to grow, allowing you to demonstrate that your hands have "germs" (although some of the microorganisms you'll find on your agar plate may very well be airborne contaminants if you don't take some precautions).


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