The polychromacity of EM radiation is tied to the mechanism of formation. A source like a light bulb or x-ray tube generates polychromatic (white light) radiation (many wavelengths) and a source likeĪ laser or a synchrotron yields monochromatic radiation. The sun's rays, when they reach earth are well collimated since the angular divergence is low.Ħ) If all waves have the same frequency (or wavelength by #2) they are called monochromatic (one color). A light bulb produces uncollimated light which spreads in all directions. Collimation refers to the divergence of the waves in a beam. The intensity which is measured is the square of the resulting amplitude, #3.Ī beams with waves which are all progressing in the same direction are termed a well collimated beam. When considering interference of two waves one adds or subtracts amplitudes of the electric field vector E. Waves which are not coherent can interfere with each other leading to a reduction of the intensity. If all waves in a beam are in-phase, that is have the same phase angle (peaks of waves coincide in space) they are called coherent. there is a particle called a photon which has no mass which carries the EM energy and has momentum, p.ĥ) X-rays and other EM radiations are generally composed of a number of photons so one can consider the relationship between different waves in a beam. The idea that EM radiation has an energy is tied to the particle view of EM radiation, i.e. l is the wavelength, n is the frequency.Ģ) The frequency and wavelength are related by the velocity of the EM wave which in vacuum is c, 'the speed of light'.ģ) The amplitude is related to the 'intensity' of the EM radiation:Ĥ) The energy of EM radiation is directly related to the energy associated with phenomena by which it is made and is not associated with the intensity. That is, at a fixed time the wave varies in Amplitude, A, with spatial position and for a given position in space the wave varies in amplitude with time.ī = B 0cos Out of phase with E by 90°Į and A have direction. Some typical disturbances in order of increasing energy are: oscillating charge in an antenna (radiowave), current flow through a tightly coiled, thin wire (light/heat), change in momentum of a charged particle at high velocity (x-rays).ġ) EM waves are described using a sin function of time and space. Similarly, an electromagnetic wave has an associated energy. A wave in a pool of water has an associated energy which is stored in the oscillation between kinetic and potential energies. TheĮlectric field is perpendicular to the magnetic field and is out of phase by 90°.ģ) Any disturbance in electo/magnetic space can create an electro-magnetic wave just as a physical disturbance in a pool of water can create a mechanical wave where kinetic and potential energies are converted. the magnetic field reaches a maximum when the electric field reaches a minimum.Ģ) Electrical generators involve the motion of a magnet on a shaft which creates an electric field and current in a surrounding coil byĪ changing magnetic field is associated with the creation of an electric field. For a sinusoidally oscillating electric field the magnetic field is out of phase by 90°, i.e. The direction of the magnetic field is perpendicular to the direction of the electric field. Here a changing electric field associated with current is related to an associated magnetic field. This magnetic field is described by one of Maxwell's laws know as the generalized X-rays are short wavelength electro-magnetic waves.ġ) We have all seen electro-magnets which are made of a coil of wire and which display a magnetic field when electricity flows through the coil. Polycrystalline Aggregates/Semi-crystalline polymers.

Experimental Methods (this will complement the lab).Calculation of the diffracted intensity.Diffraction: A basic understanding some techniques.(this is an overview of things you already should know) Crystalline structure and its relationship to the field of x-ray diffraction.What are x-rays how are they made overview of x-ray diffraction as an analytic technique.

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