| A | B |
|---|
| Angular Magnification | the ratio of the angle subtended at the eye by the image to the angle subtended at the eye by the object. |
| Bragg scattering | Scattering of X-rays by a crystal. The maxima in the intensity of the scattered X-rays appear at an angle, obeying the Bragg equation |
| Chromatic aberration | A lens defect due to the fact that rays of different wavelength (color) have slightly different focal points. |
| Dispersion | The phenomenon in which the speed of a wave depends on the wavelength |
| Far Point | The largest distance at which the eye can focus comfortably |
| Focal length | The distance of the focal point of a lens from the centre of the lens |
| Focal point | the point on the principal axis through which a ray parallel to the principal axis passes through after refraction in the lens |
| Laser | Monochromatic light produced in a laser tube that is exceptionally coherent |
| Minimum X-ray wavelength | The lowest wavelength emitted when X-ray are |
| Near point | The shortest distance at which the eye can focus comfortably without straining. |
| Popuolation inversion | The situation where there are more atoms in an excited state of an atom than in the ground state |
| Power of a lens | The inverse of the focal length of a lens. It is measured in dioptres |
| Real image | An image informed by refracted (or reflected) rays of light |
| Spherical aberration | A lens defect due to the fact that, of incident rays parallel to the principal axis, only those close to the principal axis refract through the focal point. |
| Stimulated emission | Emission of photons in an atomic transition that is induced as a result of photons incident on the atom. The incident photon energy is the same as the energy of the emitted photon |
| Two-slit interference | The maxima are given by an equation |
| Virtual image | an image formed by extensions of refracted/reflected rays of light |
| X-ray spectrum | The variation with X-ray wavelength of the intensity of X-rays produced when electrons strike a target material. The spectrum consists of (1) the continuous part formed from rapidly decelerated electrons as they are brought to rest by collisions with target atoms and (2) the characteristic part consisting of peaks in intensity |
