Optics Answers

Pls can a graph of V against I be plotted with these values?
V - I(mA)
1.1 - 110
1.3 - 120
1.4 - 130
1.7 - 150
1.8 - 170
2.0 - 190

If yes, help me plot it

c) The refractive indices of the core and cladding materials of an optical fibre are 1.51
and 1.39 respectively. Calculate the numerical aperture and light gathering capacity
of the fibre.

b) Two energy levels of an atomic system are separated by energy corresponding to
frequency 3.0 × 1014 Hz. Assume that all atoms are in one or the other of these two
energy levels, compute the fraction of atoms in the upper energy level at temperature
400 K. Take kB = 1.38×10−23JK−1 and h = 6.6×10−34Js.

a) An atomic system consisting of two energy levels, with population of higher energy
level less than that of the lower level, is in thermal equilibrium. Show that the
absorption of radiation dominates stimulated emission if radiation of appropriate
frequency is introduced into the system. Comment on the consequences of this fact
for laser action.

b) Discuss Rayleigh’s criterion for resolving power of an optical instrument. Obtain an
expression for resolving power of a microscope.

a) A plane light wave of wavelength 580 nm falls on a long narrow slit of width
0.5 mm. (i) Calculate the angles of diffraction for the first two minima. (ii) How are
these angles influenced if the width of slit is changed to 0.2 mm? (iii) If a convex
lens of focal length 0.15 m is now placed after the slit, calculate the separation
between the second minima on either side of the central maximum.

b) A plano-convex lens of radius 1.0 m is placed on an optically flat glass plate and is
illuminated by an extended monochromatic source. Assume that the point of contact
is perfect. The diameters of the 10th and 5th dark rings in the reflected light are
4.50 × 10−3m and 3.36 × 10−3m. Next, the space between the lens and the glass plate
is filled with a liquid. The diameter of the 5th ring changes to 3.0×10−3m. Calculate
the refractive index of the liquid when the ring is (i) dark, and (ii) bright, if the
wavelength of light is 589 nm.

a) Obtain the expression for shift in fringes when a thin transparent sheet is introduced
in the path of one of the waves in a double slit interference experiment.

b) Obtain an expression for elliptically polarised light resulting due to superposition of
two orthogonal linearly polarised light waves. Show that plane polarised light and
circularly polarised light are special cases of elliptically polarised light.

a) Obtain expressions for reflection and transmission amplitude coefficients when
electric vector associated with a plane monochromatic electromagnetic wave is in the
plane of incidence.