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(ii) Write down the conditions for population inversion. (3)(iii) What is pumping action? Explain the methods commonly used for

pumping action. (10)

Or

(b) (i) Explain the construction and reconstruction of a hologram. (6)

(ii) In detail explain the principle, construction and working of a four-level solid state laser. (10)

13. (a) (i) Explain in detail the losses in optical fiber with basic attenuationmechanisms. (10)

(ii) Give the advantages of fiber-optic communication. (6)

Or

(b) (i) Find the numerical aperture and the acceptance angle of an opticalfibre whose core has a refractive index of 1.5 (Refractive index ofcladding = 1.447 and Refractive index of air = 1) (4)

(ii) What is the principle of fiber optics? (2)

(iii) Explain the various types of optical fibers. (10)

14. (a) (i) Explain Planks hypothesis. (6)

(ii) State and derive Planks law of Radiation. (10)

Or

(b) (i) Derive Schrodingers time dependent and time independent waveequations. (10)

(ii) Give the physical significance of wave function . (6)

15. (a) (i) What is packing factor? Prove that the packing factor of HCPcrystal structure is 0.74. (6)

(ii) Explain the crystal structures of

(1) NaC1

(2) ZnS

(3) Diamond

(4) Graphite. (10)

Or

(b) Explain in detail the crystal defects and their types. (16)