EM and Astrophysics Definitions HL

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

Resource summary

	Created by Alexander Ekman almost 11 years ago