refraction of lens and light Flashcards
when object is at infinity [convex] -
real , inverted , diminished [ almost at a point ]
image is formed at f2
in burning glass
when object is at beyond 2f1 [convex]
real inverted diminished
image is formed btw f2 and 2f2
camera lens
when object is at 2f1
at 2f2 [formed]
same size , real inverted
in terrestrial telescope
when object is at btw 2f1 and f1
at beyond 2f2
magnified real inverted
projector
when object is at f1
formed at infinity
highly magnified real inverted
collimator of spectrometer
when object is at between lens and f1
on same side behind the object
magnified virtual upright
magnifying glass
when object is at infinity [ concave]
at the focus on same side of the lens as the object
virtual upright highly diminished
galilean telescope
when object is at any position btw infinity and optical centre in
concave
on same side between focus and optical centre
virtual upright diminished
making spectacles for myopic eye
lens formula -
1/v - 1/u = 1/f
linear magnification [m] -
length of image / length of object =v/u
power -
deviation of the incident light ray produced by a lens on refraction through it is measure of power
unit of power
dioptre
formula - D
D= 1/f [in metre ]
convex lens power is
positive
concave lens power is
negative
negative height of image = ______
inverted
positive height of image = ________
virtual
I / O =
I / O = V / U
REFRACTIVE INDEX with respect to critical angle is
sin c = 1 / refractive index glass with respect to air
sin 42 =
2/3
sin 49 =
3/4
dependence of critical angle
critical angle increase with increase in wavelength
critical angle increase with increase in temp
when will total internal reflection happens
when angle of incidence is greater than critical angle
essential condition for total internal reflection
light should move from denser to rarer
angle of incidence should be greater than critical angle for pair of media
what is spl in total internal reflection -
100% intensity of light is reflected due to this case total internal reflection is used in binocular , periscope , certain type of camera
equilateral prism -
each angle 60 *
right angled isosceles prism
45* ,90, 45
right angled prism -
30* , 90* , 60*
right angled isosceles prism used in [90* one ]
periscope
right angled isosceles prism [deviate 180*]
binocular and camera to invert image without lose of intensity
right angled isosceles prism [deviate 180*]
binocular and camera to invert image without lose of intensity
erecting prism used in
slide projector
some consequences of total internal reflection -
phenomenon of mirage
empty test tube placed in water with its mouth out shines like mirror when seen from outside
crack in glass vessel often shines
piece of diamond sparkles when viewed from outside certain distance
________ used to transmit a light signal over long distance without any lose of energy
optical fibre
total internal reflection vs mirror reflection difference
total internal reflection - image is much brighter and remains unchanged even after long time use
mirror reflection of mirror
image is less bright
gradually decrease as silver in mirror becomes old and rough
Rarrer to denser -
towards the normal
denser to rarrer -
away from the normal
intensity of refracted light decrease why?
some part gets reflected
deviation means -
the angle between direction of refracted and incident ray
snell’s law means -
incident ray , refracted ray and the normal at point of incidence all lie in same plane
ratio of sin i/ sin r=refractive index
wavelength formula
wavelength = V / F , V - SPEED , F - FREQUENCY
speed of light in vaccum -
299,792,458 or 3*10^8
refractive index formula on basis of speed -
speed of light in vacuum / speed of light in medium - absolute refractive index
refractive index is always greater than 1 why?
because always speed of light in any medium is less than speed of light in air
refractive index of diamond is 2.41 it means
light travel in air 2.41 times faster than in diamond
if refractive index is equal in both medium , what happens ?
speed of light will remain same , light will go without change in its path even when incidence is not 0
when light passes undeviated -
when refractive index is equal in both medium
angle of incidence is 0
factors affecting refractive index -
less speed in medium as compared to that in air, more refractive index
increase in temp speed of light increases
refractive index decrease
increase wavelength refractive index decrease
refractive index respect to medium 2 and 1 -
refractive index respect to medium 2 and 1 -
1/ refractive index respect to medium 1 and 2
lateral displacement -
perpendicular distance btw path of incident ray and emergent ray
dependence of lateral displacement -
more refractive index more lateral displacement
more thickness more lateral displacement
more angle of incidence more lateral displacement
light ray of single light -
monochromatic ray
deviation becomes minimum when -
angle of incidence is equal to angle of emergent
factors affecting angle of deviation -
higher refractive index greater deviation
increase in angle of prism increase in deviation
decreases with increase in wavelength
refractive index with respect to real and apparent depth
refractive index = real depth / apparent depth
shift =
real depth * [1-1/ refractive index]
dependence of shift -
higher refractive index higher shift
thicker the medium higher the shift
increase in wavelength shift decrease
