DAY 13 – DAW January

Laws of reflection and refraction from Fermat’s principle; Matrix method in paraxial optics-thin lens formula,


Q 1. State and explain the Fermat’s principle of extremum path. Discuss the cases of rectilinear propagation of light and reversibility of light rays in the context of Fermat’s principle. Using Fermat’s principle, deduce thin lens formula. [15 marks]

Q 2. What is chromatic aberration ? Obtain the condition for achromatism using combination of two thin lenses placed in contact to each other. Can this system work as achromatic doublet if both are of same material? Justify your answer. [15 marks]

Video Solution at 11 pm