Science & Mathematics Questions & Answers

Safety glass is that has been strengthened. there are two kinds of this protective glass laminated and toughened and both were discovered by accident. In the early 1900s Edouard Benedictus, a French chemist, knocked a glass flask on to the floor. Although the glass starred and cracked, it did not break. After examining the flask he realized that a coating …

Riemann Hypothesis is an important result in Mathematics whose truth or otherwise is not yet known. It asserts that an important function (called Riemann Zeta function) takes the value zero only along a certain line in the right half of the complex plane. This was conjectured by the German mathematician Gerhard Riemann in 1859 and, in spite of efforts by …

Rhinology is the study of the nose, including the sinuses, and concerns itself with medical and surgical diseases of the nasal passages and paranasal sinuses. It is becoming more important after the introduction of nasal endoscopes. A rhinologist is a specialist otolaryngologist (an ENT specialist). Rhinology was practised as early as 4000 BC – there is an inscription on the …

It is a blood group. People whose blood contains this group are referred to as being Rhesus positive. Those who lack it are called Rhesus negative.

Raman Scattering or Raman Effect is the inelastic scattering of a photon. This was first reported by CV Raman for which he was awarded the Nobel prize in 1930. When light is scattered from an atom or a molecule, most photons scatter elastically. However, a small fraction (1 in a million) is scattered inelastically. The frequency of these photons changes, …

Radar, or radio location, as it was called in the early days, is the use of radio waves to find the whereabouts of aircraft or ships. Electromagnetic waves, which include radio and light waves, all travel at the same speed. When small bursts of radio waves, fired into space from a transmitter, strike an object such as an aircraft some …

A ‘quasi-resonant’ DC to DC converter with zero-current and zero-voltage switching includes a transformer with primary and secondary windings, and periodic switching means connected in series with the primary winding. The topology of the converter is determined by selecting an input capacitor with a capacitance much lower than the output capacitor.

Push to Talk (PTT), also known as press to transmit, is a method by which we can communicate on halfduplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode. A two-way radio can both transmit and receive (a transceiver), unlike a broadcast receiver which only receives content. Two mobile phones having …

All matter consists of atoms and all atoms have protons along with other subatomic particles. When an accelerated beam of proton is incident on the target tissue like a tumour, due to their relatively enormous size, protons scatter less easily in the tissue and there is very little lateral dispersion. Therefore, the beam stays focused on the tumour shape without …

An eye that suffers from myopia as well as from hypermetropia is said to suffer from presbyopia. A person with this defect cannot see objects distinctly placed at any distance from him. To correct this defect, a person is prescribed bifocal lens that has both types of lenses — convex and concave.