Physics:
Important Questions related to chapter --Fiber Optics.
2-marks/4-marks
Q1. Define Numerical aperture, Acceptance angle.
Q2. Define Total Internal reflection of light
Q3. State the basic principle behind fibre optics.
Q4. What do you mean by attenuation in optical fibres?
Q5. Define Normalized frequency / Define V-Number. Deduce an expression for
V-Number.
Q6. Differentiate b/w single mode and multi mode optical fibre.
Q7. What do you mean by mode in an optical fibre?
Q8. Distinguish b/w step index and graded index optical fibre.
Q9. What are the qualities of a fibre optic material?
Q10. What is an optic fibre sensor?
Q11. derive the relation b/w Numerical aperture and Fractional Refractive Index.
Q12. State the advantages of fibre optic communication over copper cable
communication.
Q13. Describe (i) Splicer (ii) Coupler (iii) Connector
Q14. What do you understand by Single mode and Multimode fibre?
Q15. State major advantages of fibre communication.
Q16. Give important applications of optical fibres.
6-marks/8-marks
Q1. (a) Describe construction of an optical fiber with help of diagram. Further,
describe different factors responsible for loss of signal propagating
through a fiber.
(b) Calculate the numerical aperture, acceptance angle and
the critical angle of a fiber having core and cladding refractive indices
as 1.5 and 1.45,
respective.
Q2. (a) Derive the expression for numerical aperture, acceptance angle and angle of
acceptance cone.
(b) An optical fibre has core refractive index 1.5 and cladding refractive index
1.47. Calculate critical angle at core cladding intrface.
Q3. (a) State and explain various losses that occur in fibre transmission.
(b) State various applications of optical fibres in different fields.
Q4. (a) What are Step index and Graded index optical fibres? Explain the
propagation of signals in step index and graded index optical fibres.
(b) Calculate (i) Numerical aperture (ii) Acceptance angle of a fibre having core
refractive index 1.6 and cladding refractive index 1.58.
Q5. (a) Find the core radius necessary for single mode operation at 820 nm
of a step index fibre with n1: 1.480 and n2: 1.478.
(b) Differentiate between material dispersion and pulse dispersion. Write
down various types of losses in optical fibre.
Q6. (a) Explain the difference between a step-index fibre and graded
index fibre.
(b) What is meant by acceptance angle for an optical fibre? Show
how it is related to numerical aperture.
Q7. (a) A 20 km long fibre cable has a loss of 2 dB/Km and connector loss of
0.6 dB/Km. Find the total loss.
(b) Derive an expression for pulse broadening due to intermodal dispersion in
multimode step index optical fibre.
Q8. a) The core of a glass fibre has a refractive index of 1.6 while its cladding is
doped to give a fractional change in refractive index of 0.008. Find
refractive index of cladding and the critical internal reflecting angle.
b) Elaborate important characteristics of step index fibres.
