What is a Telescope ?

  

     A Telescope is a device that is used to observe far objects (or) bodies in the night sky such as Stars, Planets, and Galaxies. At the medieval ages, these are used to see near and distant objects both on and off the earth. These devices are used to find many exo-planets that exist far beyond some light years away from earth. Since Universe is evolving at an enormous rate, It is even sometimes difficult to these telescopes to locate celestial bodies that exist very far in deep space. These with some special abilities such as x-ray and gamma-ray vision these devices may be able to see bodies that actually difficult to capture in our infinite universe.

What is a Thermometer ?

     A thermometer is an instrument that is used to measure the temperature of a body. To measure the temperature of the body, Thermometer should be in direct contact with the body. When the Thermometer is subjected to high temperature, The Mercury will expand linearly inside the thermometer. If the Thermometer contact is broke with the body, The Mercury will regain its original position. Here raising the temperature is directly proportional to the linear variation of Mercury in the Thermometer. Mercury is the only element that is in the form of liquid at room temperature. It has a high coefficient of expansion i.e., even a slight change in temperature can be measured. Mercury has a high boiling point(356.7 ^O C) so high temperatures can also be measured.

Why do the Pressure Cookers are used on Mountains?

     When we go to high altitudes, the pressure decreases. As the pressure decreases, the boiling point also decreases and latent heat of vaporization increases. Latent heat means that the heat associated with the phase change of a substance. For example

• 0 degree centigrade of Ice to 0 degree centigrade of Water.
• 100 degree centigrade of Water changes to 100 degree centigrade of Steam.  

     Due to low pressure the boiling point is low and have latent heat of vaporization increases . At high altitudes, We use pressure cookers which is helpful to cook our food at a normal temperature like the temperature which is used to cook the food at low altitudes.

     If we use normal pots to cook food the temperature of the water increases at a high rate due to low pressure but to cook our food latent heat is required. To acquire that latent heat more heat supply is required and it takes more time to reach the latent heat. It's becoming more expensive in this manner to cook food at high altitudes. So for cost effective cooking, we use pressure cookers on Mountains.

Why does Railway Tracks expand and contract during temperature change ?

     Generally Rails are made up of steel. When steel is subjected to high temperature it expands but does not changes its shape. In solids atoms are very closely packed and when the solid is subjected to high temperature the molecules starts vibrating and the gap between the molecules increases so there will be expansion in the material. When the temperature starts decreasing, The molecules in the material starts getting close to each other so the material contracts. During Summer, the rails are subjected to high temperature and expands longitudinally but not laterally in the Winter the contracts due to low temperatures. These rails even expands and contracts during Day and Night regularly. The gap is maintained between the rails to expand freely. If this gap is not maintained the expansion is restricted and rails get bends. Due to this phenomenon, These bends may lead to accidents.     

How a Solar Eclipse ∥ Lunar Eclipse is formed ?

          Due to centrifugal and centripetal forces between the Earth and Moon, Moon revolves around the Earth. Similarly, These centrifugal and centripetal forces cause the Earth to revolve around the Sun. This helps us to study the day, date and year we will live in the present scenario. It takes 365 and 1/2 days to complete one revolution earth around the Sun is not in a perfectly circular path but in an elliptical path. This is the reason why earth experience climatical changes. It Takes 27 days to Moon to revolve around the earth. This is why sometimes the moon appears as Crescent moon in some days due to the shadow of the earth which falls on the moon and some part of the light from the sunlight falls on the moon. 

          In this Eclipse Phenomenon, These are of two types. They are: 

             (i)   Solar Eclipse 

             (ii)  Lunar Eclipse

           During the Solar Eclipse, Moon comes to a position where it completely covers the earth with its shadow which is projected towards the Earth and does not allow the sunlight to fall on the earth and makes the Sun disappear at the daytime. Here, the Moon is located exactly at the middle of the Sun and Earth but for only a short period of time.

           During the Lunar Eclipse, Earth comes to a position where it completely covers the moon with its shadow which is projected towards the Moon and does not allow the sunlight to fall on the moon and makes the Moon disappear at the nighttime. Here, the Earth is located exactly at the middle of the Sun and Moon but for only a short period of time.  

Why does a Rainbow Appears ?

                              

          Due to the process of precipitation in the earth's atmosphere, Water vapor from the clouds converts into water droplets and fall on to the earth's surface. When the water droplets separated from the clouds, These water droplets converts into a sphere shaped small balls. But the outside surface of the water droplets acts as the convex lens i.e., when the light ray falls on this outside surface of the water droplet it bends light inwards and makes it travel inside symmetrical surface of the water droplet. When the light ray travel inside the surface of the water droplet it acts as a concave lens i.e., It bends light ray and travels outward surface of the water droplet. This process happens due to light refracted from the surface of the water droplet.

            Sometimes during the rainfall, Sunlight also get projected due to the little number of clouds present in the Troposphere. This makes to happen sunlight to fall on the earth's surface and rainfall to happen at the same time. Due to this process, Sunlight which falls on the water droplets of the clouds makes the light to get refracted multiple times. Since when light falls on a transparent medium it makes the plain (or) white light into getting dispersed into seven colors i.e., VIBGYOR. These seven colors are called as Spectrum of Light. In the same way, the sunlight gets dispersed from the rainwater droplets. This refracted light separates into seven colors and makes to form as the Rainbow but to the opposite side of the Sunlight.

           

Does really Stars Twinkle at Night ?

                      Every star from our planet earth is almost located at an infinitely very large distance. Since the sun is also a star it is near to the earth, the light which is emitted from it reaches to the earth faster when compared to the other stars in the deep space. Light rays from the sun can directly penetrate from the earth's atmosphere due to the distance when it is compared to other stars.

                       In Night Sky, When the light is propagated from the stars which are at a far distance from the earth, It bends (or) Refracts from the layers of the earth's atmosphere. The bending of light is called from a transparent medium is generally called as Refraction. When the light which reaches from those stars to the human naked eye, It appears to the human naked eye as the Stars are Twinkling at the night Sky.