618597
Description
Flashcards by Alexander Ekman, updated more than 1 year ago
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Created by Alexander Ekman
over 10 years ago
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| Question | Answer |
| Define principal axis | The line which joins the centers of curvatures of the lens |
| Focal point | The point where all rays paralell to principal axis, passing through the lens, come to focus |
| Focal lengt | Distance between center of lens and focal point |
| Linear magnification | The ratio between size of image and size of object |
| Power of a lens (convex) | The extent to which light is bent p=1/f |
| Dioptres | m^-1 |
| Far point | Distance between eye and furthest object wich can be brought into focus. (Infinity) |
| Near point | Distance between eye and nearest object that can be brought into focus witout strain or aid to the eye. (25cm) |
| Angular magnification | The ration between the angle subtended by the object normally and the angle subtended by the object with an optical system |
| Light year | The distance traveled by light in one year |
| Luminosity (of a star) | The total ammount of energy (radiated by a star) per secuond (W) |
| Apparent brightness | The ammount of energy recieved per unit area per second (Wm^-1 |
| Parsec | The distance when parallax angle subtended is one arc second |
| Absolute magnitude | The magnityde as seen from 10pc away |
| Critical density | The average density of matter required for the Universe to halt its expansion |
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