Engineering Physics

Multiple Choice Questions

1. The light sources used in fibre optic communication are.    ( )
   1. LEDs
   2. semiconductor lasers
   3. phototransistors
   4. both a and b
2. Acceptance angle is defined as the _______ angle of incidence at the endface of an optical fibre, for which the ray can be propagated in the optical fibre is.    ( )
   1. maximum
   2. minimum
   3. Either a or b
   4. none of the above
3. The core diameter of single mode step index fibre is about:    ( )
   1. 60 to 70 µm
   2. 8 to 10 µm
   3. 100 to 250 µm
   4. 50 to 200 µm
4. In multimode graded index fibre, light rays travel _______ in different parts of the fibre.    ( )
   1. at different speeds
   2. with same speed
   3. both a and b
   4. none of the above
5. In optical communication system, the light detector is:    ( )
   1. Avalanche Photo Diode (APD)
   2. Positive ...