![]() Hertz performed a very interesting experiment in 1887. The radiation intensity at a given temperature increases with the decrease of wavelength, it reaches a maximum and then starts decreasing with a further decrease in wavelength. The frequency distribution of the emitted radiation from a black body depends only on its temperature. The radiation emitted by such a body is black-body radiation. The red colour lies in the lower frequency region while blue colour lies in the higher frequency region of the spectrum.Ī black-body is an ideal body that emits and absorbs radiations of all frequencies. This simply means that the frequency of the emitted radiation goes from a lower frequency to a higher frequency as the temperature increases. Have you ever observed the different colours as the iron rod becomes hotter and hotter? It starts off as a dull red colour which then becomes redder as the temperature increases.Īs the temperature rises further, it turns white and then blue. In this phenomenon, solids when heated emit radiations over a wide range of wavelengths. The best example of this is the heating of an iron rod in a furnace or over a flame. Suggested Videos on Bohr Atomic Model Black-body Radiation Line spectra of atoms with reference to hydrogen.īefore we go any further, let’s understand the phenomena of black-body radiation and the photoelectric effect.Variation of the heat capacity of solids.the ejection of electrons from a metal surface when radiation strikes it. the nature of emission of radiation from hot bodies. The wavelength, frequency, and speed of light are related by the equation:Ĭ = ν λ Particle Nature of Electromagnetic RadiationĪlthough the wave nature of electromagnetic radiation explains phenomena like ‘ diffraction‘ and ‘interference’, some other important features remain unexplained. The speed of light (c) – This is the speed at which all types of electromagnetic radiations, regardless of wavelength travel in a vacuum (3.0 x 10 8 ms -1).Its units are the reverse of wavelength – m -1 or cm -1. Wavenumber – It is the number of wavelengths per unit length.But since many waves of small wavelength make up the electromagnetic radiation, we use smaller units. Wavelength (λ) – Wavelength has the same units as the length which is the meter (m).The SI unit is Hertz (Hz, s -1), named after Heinrich Hertz. Frequency (ν) – It is the number of waves that pass a given point in one second.Electromagnetic radiation has different properties.Special instruments are needed to detect non-visible light. Visible light is the small portion around 10 15 Hz and it is only this part that our eyes can see. For example, radio frequency region around 10 6 Hz is used for broadcasting, microwave region around 10 10 Hz is used for radar, the infrared region around 10 13 Hz is used for heating and 10 16 Hz is the UV component of the sun’s rays. Different regions of this spectrum have different names and use. They all constitute an electromagnetic spectrum. Today, there are many different types of electromagnetic radiations that differ from each other in wavelength or frequency.Electromagnetic waves don’t need a medium for propagation like sound waves or water waves.The electric field in red (E axis), the magnetic field in blue (B axis), the wave propagates along the Z-axis. The electric and magnetic field of the electromagnetic wave. These fields are also perpendicular to the direction of propagation of the wave. Oscillating charged particles produce oscillating electric and magnetic fields that are perpendicular to each other.Properties of Electromagnetic Wave Motion You can download Structure of Atom Cheat Sheet by clicking on the download button below ![]() Towards Quantum Mechanical Model of Atom.How are Electrons Distributed in Different Orbits (Shells)?.Browse more Topics under Structure Of Atom Let’s understand a few simple properties of electromagnetic wave motion. Through the concept of electromagnetic radiation, Maxwell was the first to show that electricity, magnetism, and light are different manifestations of the same phenomenon. The wave nature of light was established only in the early 19th century. In the early years, scientists believed that light comprised of particles or corpuscles. These fields are transmitted as waves and are called electromagnetic waves or electromagnetic radiation.įor years scientists have speculated about the nature of light as a form of radiation. In 1870, James Maxwell proposed that when electrically charged particles move under acceleration, alternating magnetic and electrical fields are generated and transmitted.
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