Physical Optics and Principles of lighting

Part A: Multiple choice questions. Answer all the questions

1. In 1675, Isaac Newton put forward the

A) Corpuscular theory              B) Wave theory            C) Quantum theory       D) Field theory

2. The continuous locus of all particles, which are in the same phase, is called a

A) Wavefunction          B) Wavepacket            C) Wavefront               D) None of these

3. The superposition of two or more light waves and redistribution of their energies is called

A) Interference B) Diffraction                C) Polarisation  D) Specific rotation

4. The first demonstration of the interference of light waves was given by

A) Young         B) Newton       C) Fresnel        D) Maxwell

5. When light is incident on a thin film, the reflected light will not include the colour whose wavelength satisfies the equation

A) 2 µ t sin r = n λ        B)  2 µ t cos r = n λ      C) 2 µ t tan r = n λ        D) µ t cos r = 2 n λ 

6. The bending of waves around the edges of an obstacle is called

A) Diffraction               B) Polarisation  C) Interference D) Refraction

7. In Fresnel theory wavefront is divided into

A) two equal parts        B) four equal parts        C) Many  half period zones       D) None of these

8. A zone plate can be used for the wavelengths

A) Visible waves          B) Microwaves C) X-rays                     D) All of these

9. The grating equation is

A) Sinθ = (a+b) λ         B) Sinθ = nNλ              C) Sinθ = nλ                D) (a+b) Sin θ = Nλ

10. Dispersive power of a Grating is

A)= nN^*                         B) = nλ                     C)   =                  D)   =

11. The phenomenon which helped to establish the transverse nature of light is

A) Interference             B) Diffraction                C) Polarisation  D) Reflection

12. An optical device that transforms unpolarised light into polarised light is called as

A) Polaroid                 B) Interferometer          C) Grating                    D) Polarimeter

13. Thickness of the half wave plate is

A) d = λ/4 (μ_o- μ_E)       B) d = λ/2 (μ_o- μ_E)       C) d = λ/ 4(μ_o+ μ_E)      D) d = λ/2 (μ_o+ μ_E)

14. When a beam of light is observed through a rotating nicol prism, if the intensity remains uniform, then the beam is

A) Ellipticaly polarised              B) Circularly polarised  C) Plane polarised

D) None of these

15. The angle through which the plane of polarisation is rotated by the optically active substance is determined with the help of a device called

A) Polaroid                  B) Optical resonator     C) Diffractometer         D) Polarimeter                                                                                                                                                              (15×1Mark)

Part B: Answer any one question

16. Explain the production and detection of various kinds of polarized light.

17. Write a note on Fresnel’s theory of half period zones.                                              (1×10 Marks)

Part C: Answer any 5 questions

18. Write a note on quantum theory and dual nature.

19. What is scattering of light? Explain Rayleigh scattering.

20. What is SHM? Derive energy expressions for SHM.

21. What is interference? Explain constructive and destructive interference with conditions.

22. Calculate the specific rotation if the plane of polarisation is turned through 26.4^o while traversing 20 cm length of 20% sugar solution.

23. Find the number of lines in a grating to resolve in the first order sodium doublet having a wavelength difference of 6Å at 5893Å.

24. Explain different features if interference fringes. What is reflection phase shift?

                                                                                                                                    (5×5 Marks)