Physics is the most basic science which deals with the study of nature and natural occurrence. All physics and mathematics is based on some assumptions which are also called as hypothesis or postulates. For example, the universal law of gravitation proposed by Newton is a hypothesis or assumption. The universal law of gravitation says that, if we assume that any two bodies in the universe attract each other with a force proportional to the product of their masses and inversely proportional to the square of the distance between them, then we can explain all the observations in one stroke. Einstein special theory of relativity is also based on two assumptions, the constancy of speed of electromagnetic radiation (light) and validity of physical laws in all inertial frames of reference. It would not be fair to ask somebody to prove that speed of light in vacuum is constant independent of the source or observer. The various topics covered in physics include: energy, motion, speed, force, natural forces, friction, pressure, sound, magnetism, waves, electromagnetic spectrum, electric charges and black hole. Electronic devices and circuits is a branch of electronics in which the flow and control of charge carriers in the electronic devices and electronic circuits are studied. The branch of engineering in which the flow and control of electrons in vacuum or semiconductor are studied is called electronics. Diode vacuum tube was the first electronic component invented by J.A. Fleming. Later, Lee De Forest developed the triode, a three element vacuum tube capable of voltage amplification. Vacuum tubes played a major role in the field of microwave and high power transmission as well as television receivers. The various topics covered in electronic devices and circuits include: what is electronics, electron emission, vacuum tubes, atomic physics, semiconductor, semiconductor diodes, and passive components. Now-a-days computers are using everywhere: home, schools, colleges, companies, defense, navy etc. The term computer is derived from the word compute, which means to calculate. A computer is an electronic device that takes input (data) from the user and performs the series of actions under the control of set of instructions called program, produce output and stores the result for future use. The various topics covered in computer basics include: introduction to computers, brief history of computers,  development of computers, Electromagnetics is the branch of physics in which electric, magnetic fields and interaction of electric, magnetic fields are studied. The various topics covered in electromagnetics include: introduction to electromagnetics and introduction to electrostatics. The invention of satellite is the greatest achievement in the human life. Satellites are used for various purposes. Large distance communication is the major advantage of satellites. The various topics covered in satellite communication include: what is meant by satellite, types of satellites, applications of satellites and history of satellites.                                            Physics and Radio-Electronics blog