CFOT - Certified Fiber Optic Technician Fiber Optic Theory Questions and Answers

Question 1

For total internal reflection to occur within an optical fiber, what must be the relationship between the refractive index of the core (n1) and the cladding (n2)?

Accepted Answer

n1 must be greater than n2.

Answer

n1 must be less than n2.

Answer

n1 must be equal to n2.

Answer

The relationship is irrelevant to total internal reflection.

Question 2

A technician is working with a multimode fiber and notices that a light pulse is spreading out as it travels down the cable, causing the received signal to be distorted. This phenomenon, caused by different light rays taking slightly different paths of different lengths, is known as:

Accepted Answer

Modal dispersion

Answer

Chromatic dispersion

Answer

Rayleigh scattering

Answer

Absorption loss

Question 3

Which of the following is a primary cause of intrinsic attenuation in an optical fiber, resulting from microscopic variations in the density of the glass?

Accepted Answer

Rayleigh scattering

Answer

Macrobending loss

Answer

Improper connectorization

Answer

OH- ion absorption

Question 4

A fiber optic cable has a core with a refractive index of 1.480 and a cladding with a refractive index of 1.465. What is the cable's Numerical Aperture (NA)?

Accepted Answer

0.210

Answer

0.152

Answer

0.294

Answer

1.472

Question 5

When comparing single-mode and multimode fiber, which statement is generally true?

Accepted Answer

Single-mode fiber has a smaller core diameter, allowing it to carry signals over longer distances with higher bandwidth.

Answer

Single-mode fiber has a larger core diameter and is best for short-distance applications.

Answer

Multimode fiber allows for higher bandwidth and longer transmission distances.

Answer

Multimode fiber uses a laser light source, while single-mode uses an LED.

Question 6

Dispersion in an optical fiber causes pulse broadening. Which type of dispersion is caused by different wavelengths of light traveling at different velocities through the glass material?

Accepted Answer

Chromatic dispersion

Answer

Modal dispersion

Answer

Waveguide dispersion

Answer

Polarization mode dispersion