- Discovery of X-rays:
- German physicist Wilhelm Rontgen discovered X-rays in 1895 while he was investigating cathode rays (electrical discharges inside a tube containing very little air).
- He noticed that when the tube was working, some crystals lying nearby glowed, even though the tube was shielded so that no light could escape from it.
- He worked out that the cathode rays, hitting the glass of the tube, were producing other rays that made the crystals glow.
- He did some further experiments, which showed that the rays could pass through solid objects and affect photographic plates.
- This led him to make the first ever X-ray picture.
- Rontgen was at first not sure that he should announce his discovery and was worried that other scientists might not believe him.
- But soon everyone was talking about the new rays that made hidden things visible.
- Discovery of electron:
- British physicist J. J. Thomson was the first person to show that atoms contain smaller particles.
- He studied cathode rays and, by subjecting the rays to electric and magnetic fields, he showed in 1897 that they consisted of negatively charged particles.
- Thomson discovered that it made no difference what materials he used, and he concluded that the particles existed in everything.
- He believed that they were lighter and could move faster than any atom, and realized that he had found something new.
- We now call the particles electrons.
- The first liquid-fuelled rocket:
- The first rocket used solid fuels.
- They were really just big fireworks.
- Modern rockets use liquid fuel, which allows much more controllable motors to be built.
- The first liquid-fuelled rocket was launched by US physicist Robert Goddand.
- Burning petrol and liquid oxygen, it lifted off briefly from his Aunt Effie’s farm in Auburn, Massachusetts, on 16 March, 1926.
- It was another 15 years before the same idea was used in Adolf Hitler’s deadly flying bombs during the Second World War.
