A polar orbit is one in which a satellite passes above or nearly above both poles of the body being orbited on each revolution. It therefore has an inclination of 90 degrees to the poles. The polar satellite that revolve in the polar orbits are at the height of 800 km.

Radius of curvature of spherical mirror, R = 50 cm

Where R =2 × Focal length (f)

So, R = 2f or f = R/2

So, f = 50/2 = 25 cm

Hence, the focal length of the given spherical mirror is 25 cm.

Max Planck established the foundations of the Quantum theory. The theory explains the nature and behavior of matter and energy on the molecular, atomic and subatomic level. Planck was a German physicist who was awarded nobel Prize for quantum in 1918

Surface tension is the elastic tendency of a fluid surface which makes it acquire the least surface area possible.

Few applications of Surface Tension:

Surface tension allows insects (e.g. water striders), usually denser than water, to float and stride on a water surface.

Surface tension of soap solution is less, it can spread over large areas and wash clothes more effectively, since the dirt particles stick to the soap molecules. 

In soldering, addition of flux reduces the surface tension of molten tin. Hence, it spreads.

Antiseptics like dettol have low surface tension, so that they spread faster.

Surface tension prevents water from passing through the pores of an umbrella.

A duck is able to float on water as its feathers secrete oil that lowers the surface tension of water

Germanium is a chemical element with symbol Ge and atomic number 32. It is a lustrous, hard, grayish-white metalloid in the carbon group, Purified germanium is a semiconductor. In the outer shell of germanium there are four electrons, due to which it readily constitute itself as crystal lattices.

Nicholas Callan invented the Induction Coil. It is the first type of transformer and used to produce high-voltage pulses from a low-voltage direct current (DC) supply. To create the flux changes necessary to induce voltage in the secondary coil, the direct current in the primary coil is repeatedly interrupted by a vibrating mechanical contact called an interrupter.

Unit of physical quantity “Magnetic field strength(H)”, is amperes per meter (A/m).

Diastrophic forces include both vertical and horizontal movements which are caused due to forces deep within the earth. These diastrophic forces operate very slowly and their effects become discernable after thousands and millions of years. These forces also termed as constructive forces, affect larger areas of the globe and Produce meso-level reliefs, for example, mountains, plateau, plains, lakes, big faults, etc.

A pyrometer is a type of remote-sensing thermometer used to measure the temperature of a surface. Various forms of pyrometers have historically existed. In the modern usage, it is a device that from a distance determines the temperature of a surface from the spectrum of the thermal radiation it emits, a process known as pyrometry and sometimes radiometry.

The most important of all Dalton's investigations are those concerned with the atomic theory in chemistry. While his name is inseparably associated with this theory, the origin of Dalton's atomic theory is not fully understooD. It has been proposed that this theory was suggested to him either by researches on ethylene (olefiant gas) and methane (carburetted hydrogen) or by analysis of nitrous oxide (protoxide of azote) and nitrogen dioxide (deutoxide of azote), both views resting on the authority of Thomas Thomson.