Refraction Of Light Through a Glass Slab - Ray, Optics & Optical Instruments Video Lecture - Class 12

refraction of light through a glass slab
let us now perform an experiment and
find out how light gets refracted when
it is incident on a rectangular glass
slab place a rectangular glass slab on a
white sheet of paper fixed on a drawing
board
trace the boundary ABCD of the glass
slab
you
remove the glass slab
draw IO to represent the incident ray
you
draw the normal n 1 n 2 at the point of
incidence Oh
fix two pins on the incident ray IO
place the glass slab within its boundary
ABCD
looking from the other side of the glass
slab fix two pins such that the feet of
all the pins are in one straight line
remove the glass slab and the pins
mark the pin points p1 p2 p3 and p4 join
p3 p4 to represent the emergent ray o -
e join oo - oo - is the refracted ray
measure the angle of incidence angle of
refraction and angle of emergence angle
of incidence is greater than the angle
of reflection and the angle of incidence
is equal to the angle of emergence
extend Oh - EE backwards we observe that
the emergent ray is parallel to the
incident ray
the buff experiment shows that their
array of light is passing from air to
glass that is from a rarer medium to a
denser medium the refracted ray bends
towards the normal
drawn at the point of incidence the
emergent ray o - e is the refracted ray
emerging out of the glass slab oh - e is
spat a little - the incident ray this
means that the refracted ray has been
displaced from its original path by a
distance X Y this displacement is
referred to as lateral displacement we
also observe that angle oh-oh - in one -
is equal to angle R and angle E is equal
to angle I that is angle E is greater
than angle oh oh - and one - this shows
that a ray of light when travelling from
a denser to a rarer medium bends away
from the normal at the point of
incidence