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← Explorers TechnologyLenses and magnification15 minutesStd 3–5

Phone Drop Microscope

✨ A single drop of water turns a phone camera into a microscope that shows salt as tiny glass cubes.

A ray diagram showing light from a tiny salt grain bending as it passes through a domed water drop on the phone lens, spreading the picture out so the grain fills the phone screen.
How it works

🧰 You need

  • an adult's phone with a camera
  • a small piece of clear plastic sheet
  • a drop of water on a straw tip
  • salt, a leaf and a piece of cloth to look at
  • a torch

⚠️ Use an adult's phone with permission and keep the water off the phone's sockets and speaker.

👀 What you will see

Salt grains appear as clear cubes with straight edges. Cloth turns out to be threads woven over and under each other. The sharp zone is very thin, so tiny movements blur the image completely.

🧪 Do it

  1. Ask an adult for permission and hold the phone with the camera facing you.
  2. Lay the clear plastic sheet flat over the camera lens and tape its edges.
  3. Touch a tiny drop of water onto the plastic exactly over the lens.
  4. Hold the phone about one centimetre above a few salt grains.
  5. Shine the torch from the side and move the phone very slowly until the picture is sharp.
  6. Take a photo, then repeat with a leaf and with a piece of cloth.

💡 Why it happens

Light bends when it passes from air into water and out again, and anything shaped to bend light in a useful way is called a lens. A water drop pulls itself into a dome shape, so it behaves like a small, strongly curved lens and spreads the image of a tiny object over a much wider area, which is magnification. The phone camera then records that enlarged image. Real microscopes do the same job with carefully ground glass lenses instead of a wobbly drop.

🔁 Now try this

Compare a very small drop with a fatter drop and decide which one magnifies more.

🤔 Think about it

Why does the image blur the moment you move the phone by a millimetre?

🧘 Ask the Acharya

“Why does the image blur the moment you move the phone by a millimetre?” — ask him and he will explain it from your own chapters.

Ask Guru →

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