Spacecraft cannot carry large supplies of fuel and there aren’t any fillings stations in space. Instead, many have large panels of solar cells. These capture sunlight and turn it into electricity. The Sun always shines in space, so there is always electri...

Litmus paper turns red when placed in an acid solution, but blue if the solution is alkaline. This absorbent paper is the oldest and most commonly used indicator of the presence of absence of acid. Its special qualities are due to the fact that it has been so...

Wherever you live, television pictures come to you from broadcasting stations located in various cities around the country. But they may get-to-you in several different ways. Many programmes are transmitted from a local television mast. They go to the mast fr...

Archimedes, the renowned Greek scientist who lived from about 287 to about 212 BC, was asked to find out whether the King's crown was made of pure gold or of gold mixed with a less valuable metal. The story goes that one day, preoccupied with his seemingl...

In most cars is power from the engine is used to drive either the front wheels or the back wheels. This contact', with the road provides sufficient grip on all normal road surfaces. But when the roads surface is slippery such as when covered by sn...

A detergent is a substance which has the power to cleanse. This description applies to soap, as well as to soap less shampoos and washing powders. A detergent must have surface activating properties, which means it must be able to break down the surface tension of water....

It is the built-in skew or twist in a bommerang combined with its spinning motion that makes it return to the thrower. At first people believed that air, pressing on the lower flat surface and passing over the upper rounded face, was responsible for the return fight. ...

The holes in a piece of bread are made by bubbles of gas. In bread-making flour and water are mixed to form dough. Then a small amount of yeast is added td the mixture. Yeast is a type of fungus which grows very quickly when it is warm and damp. Whil...

Albert Einstein is famous for his Theories of Relativity which say that nothing in the universe is absolutely still and that all motion is connected or comparable. Einstein worked out a method of measuring the, speed of moving objects, using the three dimensions of sp...

Radioactivity is dangerous because it can expose people to harmful dose of radiation even without being aware of it. A number of small doses received over a very long time could lead to leukaemia or cancer in later life.

Radiation can lead to...