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A cylinderical optical fibre (quarter ci...

A cylinderical optical fibre (quarter circular shape) of refractive index `n = 2` and diameter `d = 4mm` is surrounded by air. A light beam is sent into the fibre along its axis as shown in figure. Then the smallest outer radius `R` (as shown in figure) for which no light escapes after incident on curved surface of fibre is:
.

A

2mm

B

4mm

C

8mm

D

6mm

Text Solution

Verified by Experts

The correct Answer is:
C
`theta_("min") gt C`
`sin theta_("min") gt sin C`
`(R-d)/R gt 1/n`
`rArr Rn-dn gt R`
`rArr R gt (nd)/(n-1)`
`R gt (2. 4mm)/(2-1)`
`R gt 8 mm`
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RESONANCE ENGLISH-PART TEST 4-Exercise
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  2. The angular dispersion produced by a prism

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  3. A cylinderical optical fibre (quarter circular shape) of refractive i...

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  4. A light is incident on face AB of an equilateral glass prism ABC. Afte...

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  5. A ray hits the y-axis making an angle theta with y-axis as shown in th...

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  6. An isosceles trapezium of reflecting material of refractive index sqrt...

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  7. A triangular medium has varying refracting index n = n(0) + ax, where ...

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  8. An object AB is placed parallel and close to the optical axis between ...

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  9. A ray of light travelling in a transparent medium falls on a surface s...

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  10. Young's double-slit experiment is conducted in water (mu(1)) as shown ...

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  11. Two coherent monochromatic light beams of intensities I and 4I are sup...

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  12. If yellow light emitted by sodium lamp in Young's double - slit - expe...

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  13. What happens by the use of white light in Young's double slit experime...

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  14. The reflecting surface of a plane mirror is vertical. A particle is pr...

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  17. A vessel of depth 2 d cm is half filled with a liquid of refractive in...

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  18. A parallel beam of light is incident on a lens of focal length 10cm. A...

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  19. Wavelength of light used in an optical instrument are lambda(1) = 4000...

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