encyclopedia

Water is clear because nothing in it reflects light. We see different things because light from them gets into our eyes. If something has nothing in it to bend or bounce light, we don’t see it. If the water has a dye in it and that absorbs some colour of light, then we will see […]

It was Newton’s observation that objects do not have their colours. The surfaces of the objects reflect some colours while absorbing others. We see only the reflected colours and that is how we are able to distinguish colours. For example, the apple will reflect the colour red while absorbing the rest. We see the red

Plants make molecules that have aromas for several reasons. From the unsavoury stink of the skunk cabbage to the pleasant smell of the sweet peas, almost all plants discharge a certain amount of pleasant or stench-like smells. However, these smells are not for the benefit of the human nose. Some of these smells, created by

Skunks use their odour to defend themselves and keep predators away. They spray a mixture of chemicals from a special gland when they feel threatened. They are notorious for their pungent and nauseating odour, basically like the smell rotten eggs have. As soon as the skunk feels that it is being attacked, it will turn

Our noses are able to discern between a pleasant smell and a stinky smell, because of the spread out of molecules of those substances/smell. Heavier, more spread-out molecules smell stinkier than compact molecules. However, there are always exceptions to the rule but in general, a substance that has spread out molecules with light electron density,

Sounds that we hear are the result of air molecules being pushed against our eardrums. When an explosive is set off, a large number of gas molecules are produced that are pushed together with air molecules to create sound waves. The faster the air is pushed, the more pressure is created, since the air has

Besides preventing people from misusing certain drugs, liquid drug delivery systems are sometimes preferred because they are faster acting than pills. Pills make bad-tasting medicines easy to swallow because only a little of the medicine actually touches the tongue before the pill is swallowed. Liquid medicines can be absorbed more rapidly than most pills. While

Our skin has a natural protective layer of oil that keeps it from drying out. If bacteria get accumulated over the skin and over the layer of natural oil, washing with soap will remove both the oil and the bacteria. Washing hands helps remove germs that can lead to diarrhoea-related sickness and respiratory infections. Furthermore,

Goggles are worn for safety purposes. Unlike food, like salt and pepper, if chemicals like acids, alkalis or abrasive powders, get into our eyes, we can neither wash them away with water nor will they get cleaned out of our eyes through tears. When we do experiments with chemicals, or when we heat something up,

It mostly isn’t. The same colours are added to conditioners that are also added to shampoos. However, before the colours are added, it is white and opaque! It appears so because the light that is reflected off them is scattered by all the tiny particles of droplets in them. It has tiny droplets of oils

The plants that grow in dry areas, and the plants that don’t lose their leaves in autumn, have to protect themselves from drying out in hot summers and in winters when the water is frozen. There are several tricks plants can use to protect their leaves from drying out: making leaves into long thin needles,

The colour of the skin and hair of a human being is decided by a pigment called ‘melanin’. In the early ages, all ancient human beings were the same colour but with the increase in population, they started spreading out all over the world. Those who lived near the equator were exposed to the sun’s

If harmful substances are released, they can pollute the environment. Damage to plants through air pollution is evident in several ways. A big change in the colour of the leaf may be visible in a short time and appear as dead tissue, or it can develop slowly as yellowing of the leaf. There may be

It is important for soil to be loose and not packed down. If the soil in the field is packed down or compacted, farmers need to plough it before they can plant their seeds. Compacted soil prevents the roots of the plants from spreading comfortably. This further limits their access to soil nutrients and also

National parks are created for the purpose of conservation and protection of the flora and fauna of the area in addition to improving the tourism of the country. People can visit parks for camping and also walking in some areas. Parks provide a safe haven to the wildlife of the area, that is, free from