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Fiber Optics: Dual Core Cable

Q- The diagram shows the end of a fiber optic cable with core refractive index 1.5 and cladding refractive index 1.4

(a) Find the critical angle at which light in the core is just totally internally reflected at X.

(b) Find the angle of incidence at A for light which is just internally reflected in the cable.

(c) Calculate the speed of light in the core.

(d) What is the time taken for light to travel 1.0 km directly down the centre of the core?

(e) Find the longest time taken for light to traverse 1.0 km of cable by internal reflections.


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