A mirage is a kind of optical illusion that occurs in hot, still weather. A pool of water suddenly appears in the distance. But on approaching, it seems to evaporate and there’s actually no water at all. You may see these mirages on roads in summer. They also occur in deserts, sometimes complete with trees, and may trick a thirsty …

When you bring a magnet close to another metal object such as a nail, the nail will be attracted towards it. This power of attraction is created by lines of force which surround the magnet. They cannot be seen, but if you place a thin sheet of paper over a magnet, and scatter iron filings on the upper side of …

A laser mouse is a type of optical mouse. It uses a laser beam which is invisible, or nearly invisible, to the human eye. The beam emitted by the laser mouse moves with the user’s hand, triggering an optical sensor system. It works in tandem with a system which tracks how far the mouse has moved by bouncing hundreds of …

Each of the vertebral bones in the spine is separated from the next by a thick and pad of fibrous tissue. The pad is roughly disc shaped and has a soft center. If the tissue is damaged, the soft center can bulge out to squeeze a nerve and so cause pain.

The cryogenic engine gets its name from the extremely cold temperature at which liquid nitrogen is stored. Air moving around the vehicle is used to heat liquid nitrogen to a boil. Once it boils, it turns to gas in the same way that heated water forms steam in a steam engine. A rocket like the Ariane 5 uses oxygen and …

The tip of a ballpoint pen, the part that writes, is very tiny metal ball in a socket. As you write, the ball spins, so that the ink is put evenly on to the paper. The side of the ball which you can’t see is in contact with the cylinder which holds the ink, so that ink always moves evenly …

Methanol does not respond to the iodoform test. In fact, the test is given by ethanol and those alcohols which possess -hydroxymethyl group or -CH(OH)- group or carbonyl compounds having acetyl functionality. Methanol can be detected by the oil of wintergreen test. In this test, 1-2 ml of methanol along with few crystals of salicylic acid are treated with concentrated …

The human eye is shaped like a ball with a bulge in the front. In the middle of this bulge is a hole called the pupil, which is the part we see as the black circle in the middle of the colored iris. The pupil lets in light to the eye. Behind it is the lens, which focuses the picture …

When you hit a table with a spoon, you hear the noise it makes quite clearly. And you also feel the spoon vibrating. But you may not realise that the noise is really made of those same sorts of vibrations, called sound waves in the air, which enable us to hear the noise. The part of the ear on the …

Despite much research, nobody is completely certain why some people catch colds while others do not. Cold research clinics take volunteers in the hope of finding the cause and cure of the common cold but the strange thing is that while some of the volunteers do catch cold, others simply do not become infected. Their natural resistance to the cold …