Science & Mathematics Questions & Answers

As it’s a safety factor, earthing is essential and mandatory. It’s an electrical connection between the exposed metallic parts of an electrical appliance or installation and the earth, regarded to have zero potential. Proper earthing provides an alternative and easy path for leakage or faulty current to flow. It ensures that any exposed conductive part of the appliance does not …

Plaster of Paris is obtained by heating gypsum or calcium sulphate dihydrate to about 140-180 degree Celsius. When heated to such a temperature, gypsum forms Plaster of Paris. The name is derived from the large deposits of gypsum in the Montmartre hill in Paris.

By breathing we inhale air that provides oxygen. Without this gas, no life can exist. When we breathe out or exhale air, it has changed. As the air made its way through our system, some of the oxygen was used up, while the amounts of carbon dioxide and water were increased. Nature keeps a balanced supply of oxygen for our …

The Blue-ray disc uses a blue (technically violet) laser operating at a wavelength of 405 nanometre (nm) to read and write data. Conventional DVDs and CDs use red and near infrared lasers, at 650 nm and 780 nm respectively. Because the Blu-ray disc data layer is closer to the surface of the disc, compared to the DVD standard, it was …

When we talk of the shape of an atom, we are referring to the shape of the imaginary volume in which the atom’s electrons orbit. Different electrons orbit at different levels and even at the same level they take different orbits. The shape of the atom depends on several factors, including the and the electrostatic forces between atomic particles. It …

It is not true that cores are always cubical. Current Transformers and Potential Transformers have ringtype cores. Power transformers have cubical cores. The ideal transformer is to have all the magnetic flux produced by one winding linking the other. This is not attained in practical transformers. Flux that does not link both windings is called leakage flux and has the …

Respirators or N95 masks can block 95% small particles that contain the H1N1 virus, which causes swine flu. These are expensive and can be used only for a single day. These masks are made of three layers of electrostaticallycharged microfibres, that block 95% particles, thus the name N95.

Sperm whale is a type of toothed whale (physeter catodon) with a very large head which has cavities containing spermaceti, a sperm oil. It is a white, waxy substance consisting of various esters of fatty acids used for making candles, ointments and cosmetics. It has no relation to sperm, the male gamete.

I personally think that the 10:10 position (sometimes 10:12 or 10:08) was adopted for pictures of clocks and watches because it is symmetric and looks better. Today the symmetric positions are both aesthetic and customary. Other symmetric hand positions are also used, but not as frequently. Examples include 8:20, 8:18, and 2:50. Reviewing some Seth Thomas clock catalog illustrations, I …

The diesel engine is more efficient than the petrol engine because of its greater thermal efficiency. This means that the ratio of the work done by the engine to the amount of heat supplied is higher. Since the heat in this case comes from fuel-oil, it is not possible to convert all the heat energy in the fuel into useful …