Radar is an object-detection system that uses radio waves to determine the range, altitude, direction, or speed of objects.
It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain.
The radar dish transmits pulses of radio waves or microwaves that bounce off any object in their path. The object returns a tiny part of the wave's energy to a dish or antenna that is usually located at the same site as the transmitter.
Section-1: General Science - Physics Question - 22
Ferromagnetism only occurs in a few substances; the common ones are iron, nickel, cobalt, their alloys, and some alloys of rare earth metals.
A ferromagnet has unpaired electrons. However, in addition to the electrons' intrinsic magnetic moment's tendency to be parallel to an applied field, there is also in these materials a tendency for these magnetic moments to orient parallel to each other to maintain a lowered-energy state.
Thus, even in the absence of an applied field, the magnetic moments of the electrons in the material spontaneously line up parallel to one another.
Section-1: General Science - Physics Question - 23
A mirage is a naturally occurring optical phenomenon caused due to:
equal heating of different parts of the atmosphere
depletion of ozone layer in the atmosphere
magnetic disturbances in the atmosphere
light rays which are bent to produce a displaced image of distant objects or the sky
A mirage is a naturally occurring optical phenomenon in which light rays are bent to produce a displaced image of distant objects or the sky.
Mirages can be categorized as "inferior" (meaning lower), "superior" (meaning higher) and "Fata Morgana", one kind of superior mirage consisting of a series of unusually elaborate, vertically stacked images, which form one rapidly changing mirage.
Section-1: General Science - Physics Question - 24
Transformers for use at power or audio frequencies typically have cores made of:
Fluorocarbons and their derivatives are useful fluoropolymers, refrigerants, solvents, and anesthetics.
Anaesthetics are categorized into two classes: general anaesthetics, which cause a reversible loss of consciousness, and local anaesthetics, which cause a reversible loss of sensation for a limited region of the body while maintaining consciousness.
Combinations of anaesthetics are sometimes used for their synergistic and additive therapeutic effects. Adverse effects, however, may also be increased.