The discovery of electromagnetic waves

At the time of Newton, one has to know that light travels straight. People also have learned that when the light field mcngenai boundary between the two opaque medium, the light is refracted (deflected). To explain these two phenomena of light, Newton thought that the glowing objects to shoot a number of particles in all directions. The particles were massless, so is not affected by gravity. Newton's law according to 1, light particles will be moving straight with constant velocity. When the light particles are stopped by an opaque barrier. a sharp image to be formed on the barrier. In 1804, Thomas Young (1773-1829), British scientist, demonstrated herhasil interference of light, which is a phenomenon in which two coherent light sources generated by the double slit forms a ribbon of light and dark bands alternate on the screen (Figure 8.1). Interference of light in detail you will learn in class XII. Interference phenomena of light can not be explained by Newton's particle theory of light. If the light was developed by the particles, the screen will receive the particles from the gap. Areas where the particles overlap each other (in the vicinity of the center P) should be uniformly brighter than the surrounding suburbs (at around the end of the Q and R), see Figure-8.1 b. This fact did not happen. Sehagai Instead, it was observed bands of light and dark bands alternating each other on the screen. Augustin Fresnel (1788-1827), French scientist, made a similar experiment with Young's interference experiment. Even Fresnel who contributed in providing mathematical theory of interference and diffraction of light (you will learn in class XII). For this work, Fresnel received an award from the Paris Academy in 1818. The failure of Newton's particle theory of light describes light interference caused across Young and Fresnel transverse wave theory of light. Both looked light as a transverse wave traveling through a medium. At that time people have learned that rapid propagation of light in vacuum is c = 3 x l08 m / s. Looking at the light as a transverse wave propagation requires a medium to very difficult for the scientists. How could anyone believe that the medium (called "ether") meets all the space, whereas those that the planets move freely through space just as the planets are moving through a vacuum that no barriers at all. James Clerk Maxwell (1831-1879). Scottish scientists who have engaged the electric and magnetic fields for years, and then proposes a theory of electromagnetic waves. In class IX, you have learned that an electric current (electric field) can cause magnetic field (a phenomenon discovered by Oersted). Opposite phenomenon is the change in magnetic field can menimhulkan electrical current (electric field), called the induced current (discovered by Faraday). Based on these two phenomena. Maxwell stated that an electric field which induce a change beruhah magnetic field is also changing. Next. magnetic field is changing electric fields induce a re-shifting. And so on so that the obtained chain process of forming an electric field and magnetic field that travels in all directions. The result is the presence of electromagnetic waves.