11th class (Fsc) Physics unit 10 MCQs
26. The magnifying power of an astronomical telescope is 10. If the focal length of objective is100 cm then what is focal length of eye-piece?
a. 1000 cm
b. 10 cm
c. 5 cm
d. 100 cm
27. For normal adjustment, what is the length of astronomical telescope if focal lengths of objective and eye piece are 100 cm and 20 cm respectively:
a. 5 cm
b. 100 cm
c. 120 cm
d. 20 cm
28. The final image see through eye-piece in telescope is:
a. Virtual, enlarge and inverted
b. Real, enlarge and inverted
c. Real, enlarge and erect
d. Virtual, enlarge and erect
29. Magnifying power of telescope is:
a. fefo
b. fe/fo
c. 1/ fe/fo
d. fe/fo
30. Which is not the essential component of a spectrometer?
a. Turntable
b. Collimator
c. Microscope
d. Telescope
31. In Michelson’s experiment the equation used to find the speed of light is:
a. 16fd
b. 16fc
c. 16/fd
d. 1/16fd
32. In Michelson’s experiment the angle subtended by a side of the eight sided mirror is:
a. 𝜋/2 rad
b. 𝜋/8 rad
c. 𝜋/6 rad
d. 𝜋/4 rad
33. In Michelson’s experiment, the relation used to find the speed of light is:
a. C = fd/16
b. C =16 f/d
c. C =16d/f
d. C =16fd
34. The first person who attempted to measure the speed of light was:
a. Galileo
b. Michelson
c. Newton
d. Huygen
35. ……… will travel faster than others through an optical fibre:
a. Infrared light
b. Ultraviolet light
c. White light
d. Visible light
36. If becomes possible to send light into inaccessible places due to:
a. Copper wire
b. Coaxial cable
c. Glass wire
d. Fibre optic
37. Information carrying capacity of optical fibre is called:
a. Immunity
b. Capacity
c. Ability
d. Band width
38. The detector in Photo-phone is made up of:
a. Selenium
b. Cadmium
c. Silicon
d. Germanium
39. Energy dissipated usually appears as:
a. P.E
b. Heat energy
c. Chemical energy
d. Nuclear energy
40. Original source of energy for biomass is:
a. Sun
b. Earth
c. star
d. Moon
41. Biomass is a potential source of:
a. Renewable energy
b. Non-renewable energy
c. Both a and b
d. Tidal energy
42. Critical angle is that incident angle in denser medium for which angle of refraction is:
a. 180o
b. 0o
c. 90o
d. 45o
43. A layer over the central core of the Jacket is called:
a. Cladding
b. Jacket
c. Rubber
d. Plastic
44. If the speed of light in vacuum is C, then its velocity in a medium of refractive index 1.3 is:
a. c/1.3
b. 1.3c
c. c
d. 1.3/c
45. Multimode graded index fibre has a core whose diameter range lie from:
a. 50 to 1000μm
b. 5 to 50μm
c. 50 to 10,000μm
d. 50 to 100μm
46. In multimode step index fibre, the diameter of core is μm
a. 100
b. 50
c. 150
d. 5
47. The diameter of the core of the single mode step index fibre is μm
a. 50 to 1000
b. 10
c. 5
d. 50
48. The optical fibre is covered for protection by a:
a. Copper Jacket
b. Glass Jacket
c. Aluminum Jacket
d. Plastic Jacket
49. Multimode step index fibre is useful for:
a. Very long distance
b. Long distance
c. Infinite distance
d. Short distance
50. The infra-red light used in the fibre optic communication system has typical wavelength equal to:
a. 1.5μm
b. 1.1μm
c. 1.7μm
d. 1.3μm
51. The light emitted from light emitting diode (LED) has wavelength:
a. 1.5μm
b. 1.3μm
c. 1.6μm
d. 1.4μm
52. The light signal in optical fibre must be generated by a device called:
a. Repeater
b. Regenerator
c. Diode
d. Generator
53. Repeaters are placed in new system at distance of:
a. 80 km
b. 30 km
c. 100 km
d. 50 km
54. Using a graded index Fibre, the time difference is reduced to about:
a. 5 ns/Km
b. 15 ns/Km
c. 1 ns/Km
d. 10 ns/Km
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