Science & Mathematics Questions & Answers

The colour of our hair depends on the amount of pigment (colouring matter) in it. Dark hair contains more of it than fair hair. This colouring matter is produced in our bodies and is controlled by the nervous system. If anything goes wrong with this control through illness but more often by wearing our in old age, then the hair …

According to a popular legend, July was named after Julius Caesar and hence it had 31 days. Later, when Augustus Caesar took over the Roman Empire, he wanted August, the month named after him, to have 31 days as well. Hence, the two extra days were taken from February, which was then left with 28 days. However, some historians don’t …

An article’s color fades when subjected to a chemical reaction in which oxygen is released. This oxygen combines with the natural coloring matter or with the dye to produce a colorless compound. Thus the color of the article becomes paler and is finally taken out together, or bleached. The most famous bleaching agent in the sun, and the process by …

Switch on the television and you are bound to see some cola advertisements. Aamir Khan, a Bollywood hero, pops open a cola and the bubbly drink fizzes to the top. Have you ever wondered what causes the countless teeny bubbles in all these soft drinks? Soft drinks are carbonated, i.e. carbon dioxide gas is dissolved in the liquid. This gas …

An iron can be worked even when it’s not hot. However, it becomes softer when heated, so working on cloth becomes easy. When iron, like any other metal, is heated, it absorbs energy which excites its molecules. This makes the metal softer. This property was known to ancient craftsmen and is used even today in producing iron implements.

Rust is iron-oxide – a molecule consisting of iron and oxygen. When rust forms, the mass of the iron object is increased by the mass of oxygen that has combined with some of the iron.

A light bulb gives off light because an electric current is passed through its filament,a thread of tungsten metal thinner than a human hair, which then becomes white hot. Sir Joseph Swan (1828-1914) in the England and Thomas Alva Edison (1847-1931) in the United States constructed the first incandescent electric lamps in 1879. They succeed in preventing the rapid burning …

An automobile is driven by an internal combustion engine which will work properly only if the right amounts of petrol and air are mixed together. The carburetor is the part of the engine where the mixing takes place. The burning of fuel in the engine is a chemical reaction in which petrol combines with the oxygen of the air to …

A winding (conductor) carrying direct current (DC) produces a magnetic field akin to a permanent magnet. The current carried by this conductor is unidirectional and steady i.e. it does not change direction or vary in magnitude with respect to time. Hence, the effect is that of a permanent magnet which simply attracts objects near the coil. The case is different …

By now you should be aware that in the bowels of the Earth all is not still. On the contrary, it is very active. One obvious example the the Earth’s internal working is the activity of volcanoes. There are many famous instances of a volcano erupting and spewing white hot, molten rock from it mouth; if you have been to …