light - reflection and refraction Flashcards
(21 cards)
what makes things visible?
An object reflects light that falls on it.
This reflected light, when received by our eyes, enables us to see things.
how do we know light travels in a straight line?
The fact that a small source of light casts a sharp shadow of an opaque object points to this
straight-line path of light, usually indicated as a ray of light.
how can we see through a transparent med.?
We are able to see through a transparent medium as light is transmitted through it
laws of reflection
1) angle of incidence = angle of reflection
2) IR, RR and N lie on the same plane
plane mirror image
- virtual and erect.
- The size of the image is equal to that of the object.
- The image formed is as far behind the mirror
as the object is in front of it. - laterally inverted.
define spherical mirrors
- part of hollow sphere of glass or polished metal
- The reflecting surface of a spherical mirror may be curved inwards or outwards
define concave mirror
spherical mirror whose reflecting surface is curved inward -> ))
def. convex mirror
spherical mirror whose reflecting surface is curved outward
aperture
diameter of reflecting surface of spher. mirror
pole, P
centre of reflecting surface of spher mirror
centre of curvature, C
centre of the sphere of which a spherical mirror is a part.
radius of curvature, R
radius of sphere of which spher mirror is a part -> frm C to any point on the mirror
principal axis, PC
imaginary straight line passing thru C and P
principal focus, F
concave - point on princi axis at which all light rays parallel to PC converge after reflection
convex - point on PC FROM which light rays that r parallel to PC APPEAR TO diverge
focal length, f
dist between P and F
f=2R
reflection
phenomenon in which light rays striking a reflective surface (like mirror) are sent back in the same medium
what happens to a ray of light passing thru the centre of curvature of a spher mirror?
cave AND vex - reflected back on the same path
what happens to a ray of light passing thru/converging at the focus of a spher mirror?
both - reflected ray is parallel to PC
what happens to a ray of light incident at the pole p e of a spher mirror?
reflected back such that <i></i>
what happens to a ray of light parallel to the PC of a spher mirror?
cave - passes thru focus
vex - appears to be coming frm the focus
refraction of light
when travelling obliquely from one medium to another, the direction of propagation of light in the second medium changes. This phenomenon is known as
refraction of light.
