The correct answer is False.
A single-mode step-index fiber allows propagation of only one transverse electromagnetic wave, while a multimode step-index fiber allows propagation of multiple transverse electromagnetic waves.
A step-index fiber is a type of optical fiber in which the refractive index of the core is greater than the refractive index of the cladding. This causes light to be guided down the fiber by total internal reflection.
The number of modes that can propagate in a step-index fiber depends on the wavelength of light and the diameter of the fiber. For a given wavelength, the number of modes increases as the diameter of the fiber increases.
A single-mode fiber is a type of step-index fiber that can only support one mode of propagation. This is because the core diameter of a single-mode fiber is very small, typically around 8-10 micrometers. This small core diameter limits the number of modes that can propagate in the fiber.
A multimode fiber is a type of step-index fiber that can support multiple modes of propagation. This is because the core diameter of a multimode fiber is larger than the core diameter of a single-mode fiber, typically around 50-62.5 micrometers. The larger core diameter allows more modes to propagate in the fiber.
Single-mode fibers are typically used for long-distance communication, while multimode fibers are typically used for short-distance communication.