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Roentgen

In 1895 a German professor Wilhelm Konrad Roentgen discovered a new kind of invisible rays. These rays could pass through clothes, skin and flesh and cast the shadow of the bones themselves on a photographic plate. You can imagine the impression this announcement produced at that time.

Let us see how Roentgen came to discover these all-penetrating rays. One day Roentgen was working in his laboratory with a Crookes tube. Crookes had discovered that if he put two electric wires in a glass tube, pumped air out of it and connected the wires to opposite electric poles, a stream of electric particles would emerge out of the cathode (that is, the negative electric pole).

Roentgen was interested in the fact that these cathode rays made certain chemicals glow in the dark. On this particular day Roentgen was working in his darkened laboratory. He put his Crookes tube in a box made of thin black cardboard and switched on the current to the tube. The black box was lightproof, but Roentgen noticed a strange glow at the far corner of his laboratory bench. He drew back the curtains of his laboratory window and found that the glow had come from a small screen which was lying at the far end of the bench.

Roentgen knew that the cathode rays could make the screen glow. But he also knew that cathode rays could not penetrate the box. If the effect was not due to the cathode rays, what mysterious new rays were causing it? He did not know, so he called them X-rays.

Roentgen placed all sorts of opaque materials between the source of his X-rays and the screen. He found that these rays passed through wood, thin sheets of aluminium, the flesh of his own hand; but they were completely stopped by thin lead plates and partially stopped by the bones of his hand. Testing their effect on photographic plate he found that they were darkened on exposure to X-rays.

Roentgen was sure that this discovery would contribute much for the benefit of science. Indeed, medicine was quick to realise the importance of Roentgen's discovery. The X-rays are increasingly used in industry as well.

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