A fibre optic cable has a transparent core of refractive index 1.6 and the cladding has a refractive index of 1.5. An optical signal travels along path A and another signal travels along path B such that it strikes the core – cladding interface at an angle of incidence `theta` that is just greater than the critical angle. Length of the cable is 1500 m.
(a) Find the time difference between the two signals reaching the other end of the cable.
(b) A digital signal shown in the Figure. is transmitted through the cable. Find maximum frequency so that the crest from path A never arrives with a trough from path B at the receiving end of the cable.
