Optics Flashcards
what is the propagation speed for light
c=3x10^8
what is the refractory index for air
1
law of reflection is what
light bounce off
e.g. mirror
angle in is equal to angle out
law of refraction what is it
object looks broken
e.g. pencil in a water of glass
in the law of refraction what is the equation
n1sin(theta1) = n2sin (theta2)
what is the equation for total internal reflection
theta = sin^-1 (n2/n1)
if a lense is converging what sign will this be
positive
if a mirror is concave what sign will it be
negative
what is the mirror/ thin lense equation
1/image distance + 1/object distance = 1/focal length
if magnification smaller than 1 this means that the image is
smaller than the object
if magnification bigger than 1 what does this mean to the image
image is larger than the object
object larger than the wavelength of light - what characteristics and what what optics
ray characteristics
geometric optics
objects smaller than wavelength - what characteristics and what optics
wave characteristics
wave optics
the behaviour of light in a medium is dictated by the mediums
refractive index
why is the speed of light through its matter is less than its vaccum
atoms and particles in material interact with light - therefore hindering speed
if the incident angle is greater than the critical angel then where are all light rays reflected
internally
when then refractive index in medium one is higher than medium 2 what will occur
total internal reflection
if a lense has a convering effect what lense is this
convex
point of convergence and point of divergence of light rays passing through lens or reflecting off a mirror is called what and labelled what
focal point
F
distance of focal point to lens is called what and labelled as what
focal length
f
greater effect a lens has on light rays more what
optical power
real or virtual - when light rays pass through image point
real
real or virtual - when light rays DON”T pass through image point - light rays appear to come from image point of the same side as object
virtual
can virtual object be presented on to a screen
no
a concave lens can form what type of image
virtual only
negative m revers to inverted/ upright image
inverted
what is the process:
image distance from the lens to retina (di) is fixed so the lens must adjust its focal length to focus images on the retina for objects at different distances
accomodation
the distance to the closest object that can be seen clearly is called what
near point
the distance to the closest object that can be seen clearly is called what
near point
are the light rays from near objects not parallel what does this mean for what type of lens would be
true
- lens must be more converging
what muscle makes the lens thicker to be more converging and thinner to be less conversing
ciliary muscle
equation for power is
P = 1/f
what is the normal near point for a 25 year old
25cm
what eye defect has shortsightedness
- inability to see far objects clearly
- far point
myopia
what eye defect has the
- inability to see close objects clearly
- near point further away from normal
hypermetropia
what eye defect has this
near point gets further away
- not a disease - normal part of ageing
presbyopia
what eye defect is this
- entire image not completely in focus, but parts are
- corrected by wearing glasses
astigmatism
bending of wave around edged of an opening
defraction
what is it called when two waves cross each other
interference
in phase - are when peaks and troughs are in line what will this mean for resultant wave
what type of interference is this called
twice amplitude
- constructive interference
out phase is when peaks and troughs dont align what will the resultant amilitude be
- what type of interference is this
resultant is zero
destructive
the smaller the aperture the _____ the angle of diffraction
larger
the limit to the ability of any optical instrument to produce distinct images of objects which are very close together is called what
resolving power or resolution
glasses with convering or diverging lenses are able to correct hypermetropia
converging
is it possible for a converging lens to form a virtual image -
no because this means that it would be a convex lens to be converding
only concave lens (diverging) and convex mirrors are able to produce virtual image
is it possible for a diverging lens to form a real image
no because only concave (diverging) lens are able to produce virtual
what is the formular for refractive index
n=c/v (c is a constant)
a convex lense when do>F what does this mean for an image
real, enlarged, inverted
a convex lens do<F what does this mean for image
Alway virtual, enlarge and upright
in concave lens image will be
alway virtual, reduced and upright
in convex mirror image will be
virtual, always reduced and up right
in concave mirror (do>F) image will be
image real, enlarged and inverted
in a concave mirror (do<) image will be
always virtual, enlarged and up right
