unlocked puzzles of science

  Wave nature of Electromagnetic Radiations Maxwell , in 1873 , showed theoretically that an oscillating electrical circuit should radiate electromagnetic waves propagating with the velocity of light.  The main features of this theory are : 1 .  Energy may be emitted from any source such as heated rod or filament of a bulb through which electric current is passed. Energy is emitted continuously in the form of radiations (waves).  2.  These waves are associated with oscillating electric field and magnetic field. These two fields are perpendicular to each other and perpendicular to the direction of propagation of the radiation as shown in the figure.  Fig: Oscillating electric and magnetic fields emitted by charged particles.  3.  The radiations possess wave nature. Their velocity is equal to the velocity of light, i.e, 3×10⁸ m/sec. The radiations are called electromagnetic radiations or electromagnetic waves.  4. Electromagnetic waves do not require any material medium for propagation.

 Particle nature of radiation (Or light)  Electromagnetic wave theory explains the properties of light such as interference , diffraction and polarization . But certain phenomena like photoelectric effect, black body radiation, line spectra of atoms with special reference to hydrogen, variation of heat capacity of solids as a function of temperature, could only be explained by quantum (photon) theory of radiation in which radiation is considered as a particle nature.   It means that radiation has a dual nature, both as a particle and as a wave. By taking an example it could be easier to explain.  Example:  when we see an object, both the aspects are important. The gathering and focusing of light by the eye-lens is well described by the wave picture, while absorption of light by the retina is described by the photon picture of light.  In 1901,Planck put forward the particle nature of electromagnetic radiations(Planck's Quantum Theory)  to explain the phenomenon of black body radiati

 Dark matter Roughly 80% of the mass of the universe is made up of material that scientists cannot directly observe , known as dark matter. This bizarre ingredient does not emit light or energy. Since atleast the 1920s , astronomers have hypothesised that the universe contains more matter than seen by the naked eyes. Support for dark matter has grown since then, and although no solid direct evidence of dark matter has been detected, there have been strong possibilities in recent years. Originally known as the , "missing mass", dark matter's existence was first inferred by Swiss American astronomer Fritz Zwicky, who in 1933 discovered that the mass of all the stars , in the coma cluster of galaxies provided only about 1% of the mass needed to keep the galaxies from escaping the cluster's gravitational pull. Two varieties of dark matter have been found to exist. The first variety is about 4.5% of the universe and is made of the familiar baryons. Most of the baryonic or

Introduction   The world as we know it has three dimensions of space - length,width  and  depth  and one dimension of time.  But there's the mind - bending possibility that many more dimensions exist out there. Beyond these three visible dimensions, scientists believe that there may be many more. The development of string theory in early 1988 from studies of the problem of supersymmetry breaking by Antoniadis et al. In fact ,the theoretical framework of superstring theory posits that the universe exists in ten different dimensions. These different aspects are what govern the universe, the fundamental forces of nature and all the elementary particles contained within. Theories that suggest extra dimensions predict that,in the same way as atoms have a low - energy ground state and excited high - energy states, there would be heavier versions of standard particles called Kaluza - Klein States , would have exactly the same properties as standard particles but with a great mass. Kaluza

Introduction We don't know what happened at the exact instant of the big bang. However, over the last few decades physicists have pushed our understanding back further and further to very beginning of time and applied the known laws of physics to arrive at the rough timeline of what happened during the very early evolution of the universe. The vast majority of scientists believe in the  big bang theory  , which would have started the universe we know. According to the theory, about 13. 7 billion years ago all the matter that constitutes the universe was concentrated in the single point, which exploded, giving rise to everything we know. Before our universe existed, there would be another one before it, which also emerged from a supermassive point, expanded and began to shrink, reaching the singularity of the big bang.  The universe is 13.7 billion years old, with a margin of error of 0.2 billion more or less. To reach this figure, scientists have struggled for almost 80 years.  The

 Introduction For as long as humans have been grazing at the night sky, the question of how far can see into it has fascinated astronomers. The revolutionary observations made by Edwin Hubble in the late 1920s were the first direct evidence that the universe was not static. The systematically increasing spectroscopic redshift observed in increasingly distant galaxies was a clear sign that the universe expands. Because the universe is expanding, the sphere of what we can see is not defined simply by the age of the universe multiplied by the speed of the light. This is because the universe is expanding ;the distance between every point of the fabric of spacetime is forever increasing, a growth that affects the paths of photons. For a long time this expansion was believed to be slowing down due to the combined gravitational pull exerted by all the matter in the universe. However, at the end of the 1990s the measured dimming of Type la supernovae with increasing redshifts revealed that thi

Introduction The vast empty space surrounding the planets and stars is called as the universe. It consists of dark matter,dark energy ,stars and galaxies. Both cyclic and unpredictable processes are found to happen in the universe. Cosmology is the study of nature and origin of the universe. Thousands of years before smartphones or Mario Kart, people entertained themselves by peering at the night sky and connecting the stars to create pictures called constellations- of animals ,objects and legendary heroes. Today ,the heavens are no less entertaining but a bit mysterious mystery where so many great minds working to solve the unlock puzzles of secrets. Universe is believed to have originated about 15 billion years ago through big bang (Lemaitre,1931) or thermonuclear explosion of an extremely sense entity. It began to expand. Cosmic material is still expanding. Big Bang theory The 'big bang' is the name for the leading  theory behind the birth of everything:atoms,light ,gravity

 Introduction The periodic table of the elements is one of the most powerful icons in science ; a single document that consolidates much of our knowledge of chemistry.For over a century, millions of children have started out every year on their journey into the fascinating world of chemistry with the periodic table of the chemical elements. Hundreds of versions of the periodic table have been proposed, and a variety of methods have been applied to its analysis.Throughout its long history, the periodic table has been disputed, altered and improved as science has progressed and as new elements have been discovered. But despite the dramatic changes, no revolution in the basic nature of the periodic system. After evolving for over 200 years through the work of many people, the periodic table remains at the heart of the study of chemistry  It ranks as one of the most fruitful ideas in the modern science. Efforts of many physicists and chemists  The modifications to quantum theory made by We