चिकित्सा एंडोस्कोपी में प्रकाशिक तन्तु का क्या उपयोग है?

For a step-index optical fiber, the total number of guided modes (M) propagating through the fiber is related to the fiber parameters. Which of the following proportionalities correctly represents the relationship involving the core diameter (d) and the wavelength of light (λ)?

For light traveling from a core of higher refractive index to a cladding of lower refractive index, total internal reflection is possible. However, if an input specifies a step-index fiber with a core refractive index n1 = 1.25 and a cladding refractive index n2 = 1.42, light cannot guide via total internal reflection since n1 < n2. If the indices are inverted such that n1 (core) = 1.42 and n2 (cladding) = 1.25, calculate the critical angle θc at the core-cladding interface.