P14 Light Flashcards
angle of incidence
angle between the incident ray and the normal
angle of reflection
angle between the reflected ray and the normal
concave (diverging) lens
a lens that makes parallel rays diverge (spread out)
convex (converging) lens
a lens that makes light rays parallel to the principal axis converge (meet) at a point
diffuse reflection
reflection from a rough surface - the light rays are scattered in different directions
focal length
the distance from the centre of a lens to the point where light rays parallel to the principal axis are focused (or, in the case of a diverging lens, appear to diverge from)
magnification
the image height ÷ the object height
magnifying glass
a converging lens used to magnify a small object which must be placed between the lens and its focal point
normal
straight line through a surface or boundary perpendicular to the surface or boundary
opaque object
an object that light cannot pass through
principal focus
the point where light rays parallel to the principal axis of a lens are focused (or, in the case of a diverging lens, appear to diverge from)
real image
an image formed by a lens that can be projected on a screen
refraction
the change of direction of a light ray when it passes across a boundary between two transparent substances (including air)
specular reflection
reflection from a smooth surface. Each light ray is reflected in a single direction
translucent object
an object that allows light to pass through, but the light is scattered or refracted
