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🧪 Science 💡 Light and sound

X-rays

A chest X-ray (right), showing the shadows of the heart, lungs and ribs. Pictures like this help doctors find lung diseases, broken bones and other problems inside a patient's body. X-ray pictures are taken with an X-ray machine (left), which…
A chest X-ray (right), showing the shadows of the heart, lungs and ribs. Pictures like this help doctors find lung diseases, broken bones and other problems inside a patient's body. X-ray pictures are taken with an X-ray machine (left), which…

📖 In short

X-rays are invisible rays that can pass through skin and flesh, but bones stop them. That's why doctors use them to take pictures of our bones from the inside and see if anything is broken. The German scientist Röntgen discovered them in 1895.

🤩 Did you know?

  • Röntgen discovered X-rays in 1895, and the first X-ray picture was of his wife's hand!
  • Lead absorbs X-rays better than most materials.
  • Scientists also use X-rays to study stars and galaxies.
  • Röntgen won the first Nobel Prize in Physics.

🔎 Find out more

🌟 Why “X”?

When Röntgen discovered these rays he didn't know what they were, so he called them “X-rays”, because the letter “x” stands for the unknown in mathematics, like the letter “sīn” in Arabic. That's why in Arabic they're called “sīn rays”.

🔍 Pictures of bones

On an X-ray picture bones look white because they stop the rays, while flesh looks dark gray because the rays pass through it. So the doctor can see fractures, and dentists can see decay.

💡 At airports

Airports use X-ray machines to see what's inside suitcases without opening them, keeping passengers safe.

🎯 Carefully

X-rays are powerful, and too many harm the body. So the doctor puts a heavy lead apron on the patient to protect the rest of their body, and the staff leave the room while the picture is taken.

📸 More pictures

X-rays have many industrial uses because they can pass through things so well. They're used to check the structure of a jet engine (top), and an X-ray picture like this reveals cracks and other structural flaws that may not show on the surface.
X-rays have many industrial uses because they can pass through things so well. They're used to check the structure of a jet engine (top), and an X-ray picture like this reveals cracks and other structural flaws that may not show on the surface.
How an X-ray machine works
How an X-ray machine works
X-rays help archaeologists examine ancient things like these two mummies. The picture shows the skeletons of a boy and a girl under the thick cloth wrappings.
X-rays help archaeologists examine ancient things like these two mummies. The picture shows the skeletons of a boy and a girl under the thick cloth wrappings.

🧩 Test yourself

1 Why do doctors use X-rays?

2 Which material protects the body from X-rays?

3 Which picture shows “X-rays”?

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