Science & Mathematics Questions & Answers

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 …

When a person blows out a trick birthday candle, it re-ignites itself in a few seconds. The key about a normal candle that is important to a trick candle is the moment after one blows out a candle. Normally, there is a burning ember in the wick that causes a ribbon of paraffin smoke to rise from the wick. That …

A special clear coating is applied to the lenses, either on the front or back of the lens, or sometimes both sides. It’s a transparent coating and can be applied to any colour of lens including clear. The UV-filtering effect, however, is more complex. UV-filtering lenses are coated with special chemicals that allow light to pass through them, but reflect …

As the flagellae of the cells inside the sponge beat the water, a current is set up and water is drawn through the tiny pores into the center of the sponge and then driven out through the hole at the top. Suspended particles of food in the water are caught on the flagellae of the cells and passed back to …

Solar cells use photovoltaic cells to convert sunlight directly into electricity by converting photons (light particles) into electrons (negatively charged particles). Photovoltaic cells are made of semiconductors and silicon, mixed with other material.