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Across 1. the bright central region in the interference pattern of light and dark lines produced in diffraction 4. the ability of an instrument to separate two images that are close together 5. the property of a material that, when analyzed, reveals the material’s stress distributions 9. confining the vibrations 10. an instrument that uses a diffraction grating to visually observe spectra 12. the change in direction of particles or waves as a result of collisions with particles 15. the leading edge of a continuous crest or trough 16. the bending effect on a wave’s direction as it passes through an opening or by an obstacle 18. the angle between the reflected wave front and the barrier, or the angle between the reflected ray and the normal 19. occurs when waves diminish one another producing a resultant wave of lower amplitude than the given waves 21. of one colour, or one wavelength 23. the property of certain crystals (e.g., calcite) to split an incident beam of light into two 24. the progressively less intense bright areas, outside the central region, in the interference pattern 25. a plastic, light-polarizing material

Down 2. the angle between the normal and the refracted ray, or between the refracted wave front and the boundary 3. the bending effect on a wave’s direction that occurs when the wave enters a different medium at an angle 6. periodic disturbance where particles in the medium oscillate at right angles to the direction in which the wave travels 7. property of a substance whereby a transparent material rotates the plane of polarization of transmitted light 8. occurs when waves build each other up, producing a resultant wave of greater amplitude than the given waves 11. a line of destructive interference 13. the angle between the incident wave front and the barrier, or the angle between the incident ray and the between the incident ray and the 14. the air between two pieces of optically flat glass angled to form a wedge 17. a straight line drawn perpendicular to a barrier struck by a wave 20. a straight line, drawn perpendicular to a wave front, indicating the direction of transmission 22. a natural (e.g., clouds) or artificial (e.g., filters) means to achieve polarization