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191. Marie Curie and Lise Meitner (Score: 1.0000)
As the IOP hosts a talk on pioneering women in physics, we profile two of those featured: Marie Curie and Lise Meitner. 1898 Marie Curie and husband Pierre identify new elements – polonium and radium – and discover that thorium is also radioactive. 1938 Lise Meitner, Otto Frisch, Otto Hahn, and Fritz Strassmann carry out experiments involving bombarding uranium with neutrons and discover nuclear fission of heavy elements.

192. Topic of the Moment: lasers (Score: 1.0000)
The underlying theory behind the laser was first developed by Albert Einstein in 1917, but a working device wasn’t produced – operating at microwave frequencies – until 1953. Improvements since then have meant that modern lasers can work in continuous operation rather than having to be pulsed, have a wider range of frequencies of light that they can produce, and both a higher maximum power and greater efficiency at lower cost. in science fiction, lasers had not been put ...

193. Blooper reel (Score: 1.0000)
An aether of some sort was postulated in both the particle and wave theories of light. And Augustin Fresnel included it in his wave theory as the medium through which waves of light propagate. Of the two competing theories, the wave explanation won out when James Clerk Maxwell combined four equations of electricity and magnetism to produce a wave equation in which the propagation speed was the speed of light.

194. Topic of the Moment: fuel cells (Score: 1.0000)
Fuel cells convert hydrogen and oxygen into water, producing electricity in the process. The type typically considered for transport applications e proton exchange membrane fuel cells. Unlike batteries, which convert stored chemical energy to electricity, fuel cells need a constant supply of hydrogen and oxygen in order to work.

195. Topic of the Moment � Proton Beam Therapy (Score: 1.0000)
As Ashya King begins to receive proton beam therapy for a brain tumour, we look at what the treatment is and how it works. Proton beam therapy works similarly to conventional radiotherapy, except that beams of protons, instead of X-rays, are used to kill cancer cells. Two advanced radiotherapy centres offering high-energy proton beam therapy are set to open in 2018.

196. Topic of the Moment – cryptography (Score: 1.0000)
Decoding a message needs the encryption key – i.e., the way in which text is converted between plain text and ciphertext. It’s a key made up of a random string of text that converts the original message via modular addition. Subtracting the key again restores the plain text, which can then be read by the recipient of the message.

197. Topic of the Moment � weights and measures (Score: 1.0000)
The International Prototype Kilogram (IPK) is kept at the International Bureau of Weights and Measures in Paris, and the metallic cylinder has been used to define the kilogram since 1889. Since the kilogram is defined as being the mass of the IPK, then if that block gets heavier the kilogram simply becomes a larger mass unit than it previously was. For example the unit of force, the Newton, is defined as that required to accelerate a mass of one kilogram at a rate of one metre per second ...

198. Volcanic ash (Score: 1.0000)
As passengers stranded by volcanic ash back in April publish a collaborative magazine, we take a look at how ash affects jet engines. The makeup of ash Volcanic ash is made up of small pieces of rock and glass no more than 2mm across. A jet engine’s weak spot Jet engines and rockets work on the same basic principle.

199. Topic of the moment – the transit of Venus (Score: 1.0000)
The transit of Venus is much like a solar eclipse, with the planet crossing in front of the Sun as viewed from Earth. By watching a transit of Venus and measuring the time taken for it to cross the entire Sun’s disc as viewed from two points on Earth separated by large latitudes, the distance from Earth to Venus can be worked out using the parallax method. After the 1882 transit, Simon Newcomb combined data from the prior four events and determined the distance to the Sun to an ...

200. Television (Score: 1.0000)
When the beam of electrons hits the screen, it excites a fluorescent coating – usually phosphor – which then glows. Colour televisions use three electon guns and three types of screen coating that glow red, blue and green, combining these in various proportions to produce any colour. Screens consist of many pixels made up of a layer of liquid crystal between transparent electrodes – in colour LCDs the pixels are divided into three cells coloured red, green and blue using ...

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