6. What is the maximum core diameter for a fiber if it is to operate in single mode at a wavelength of 1550 nm if the N.A. is 0.12? 7. Consider a fiber with a 25 μm core radius, a core index", = 1.48 and A = 0.01 a. if λ=1320nm, what is the value of V and how many modes propagate in the fiber? b. What percent of optical power flows in cladding? c. If the core-cladding difference is reduced to A = 0.003, how many modes does the fiber support and evaluate the percentage of optical power that flows in the cladding in this case?