EC8751_OC_MODEL III_PART B

Fiber optic cable operate at frequencies near

• 2 GHz

• 20 MHz

• 200 MHz

• 800 THz

A typically structured glass multimode step index fiber shows as variation of attenuation in range of ___________

• 1.2 to 90 dB km^-1 at wavelength 0.69μm

• 3.2 to 30 dB km^-1 at wavelength 0.59μm

• 2.6 to 50 dB km^-1 at wavelength 0.85μm

• 1.6 to 60 dB km^-1 at wavelength 0.90μm

Multimode graded index fibers with wavelength of 0.85μm have numerical aperture of 0.29 have core/cladding diameter of ___________

• 62.5 μm/125 μm

• 100 μm/140 μm

• 85 μm/125 μm

• 50 μm/125μm

............. categories exists in case of cable design

• 2

• 3

• 4

• 5

Fiber optics was invented by .........

• Thomas Mensah

• Thomas Edison

• John Henry Holmes

• None of the above

Multimode graded index fibers use incoherent source only.

• True

• False

In a laser structure, the existence of standing waves is possible at frequencies for which the distance between the mirrors is an integral number of ________

• λ / 2

• λ / 4

• λ / 6

• λ / 8

Consider a crystal of ruby laser whose length is 6 cm and the refractive index is 1.8, emits the wavelength of about 0.55 μm. What will be the value of number of longitudinal modes?

• 3.9 x 10⁵

• 4.9 x 10⁵

• 5.6 x 10⁵

• 7.7 x 10⁵

A single mode optical fiber has a core diameter of _____ nm

• 0.1

• 0.01

• 0.2

• 0.05

The handheld optical power meter has a measurement accuracy of ________

• 0.01 dB

• 0.25 dB

• 0.8 dB

• 1 dB