some random stuff Flashcards
Identify the classifications of light transmitting abilities.
- OPAQUE. doesn’t allow light to pass through.
- TRANSPARENT. allows light to pass through and objects can be seen clearly through it.
- TRANSLUCENT. allows light to pass through such that it is not possible to recognize objects seen through it.
apparent or angular size alpha =
tan α = d/D
when is a luminous object treated as a point source?
when its angular size approaches 0.
what do we call an object that cannot be considered a single point?
an extended object.
a light ray is?
is an imaginary line along which light energy propagates
State the principle of rectilinear propagation of light.
In a homogeneous medium, light propagates along directed straight lines called RAYS.
the shadow from a point source is
of sharp edges and equal distribution of darkness.
the shadow from an extended source has
diffuse edges. it has two regions: a dark central UMBRA. and a ring of partial shadow called the PENUMBRA.
a collection of light rays is called a ____
beam
three different types of beams. identify each.
Parallel Beam: a collection of parallel rays propagating in the same direction. (sunlight striking a magnifying glass)
Divergent Beam: a collection of rays that emanate or appear to emanate from a single point. (electric torch)
Convergent Beam: a collection of rays that meet or appear to meet at a single point. (the beam emerging from a magnifying glass exposed to sunlight)
what happens when light does not strike anything?
all you see is black.
when does light become visible?
when it enters your eye, and even then, all you see is the illuminated dust particles.
what is the function of an optical system?
to form an image, through multiple optical manipulations performed over the light beam from the object.
what is an optical system?
a combination of optical components such as lenses and mirrors that forms an image for a given object. (luminous or non-luminous)
The image of a point object is____
a point where light rays seem to come out.// the intersection of two emergent rays.
in a kaleidoscope, what happens when the angle between the mirrors DECREASES?
number of images increases. this is until the mirrors become parallel, and the images will then become INFINITE.
what is refraction?
the bending of light which occurs when light passes from one transparent medium to another.
true or false? in different mediums light travels at the same speed.
FALSE. different media = different speeds.
two factors affect the amount of refraction. STATE them.
A. change in index of refraction
B. the angle of incidence.
define index of refraction.
the ratio of the speed of light in vacuum to the speed of light in that medium. n=c/v
the index of refraction for a homogeneous medium is ____
constant
two mediums are being compared according to their indices of refraction. medium A has an n=1.5 and medium B has an n=1.36. what do we term the medium with the larger index of refraction?
as optically denser
the denser the material, the ____ is light in that material, the ______ the refraction, & the ____ the angle of incidence.
slower, greater, smaller
