Entry Test MCQ :: Optical Instruments

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21.

Dispersional effect may produce error in light signals. This type of error

A.	single mode step index fibre	B.	multimode step index fibre
C.	multimode graded index fibre	D.	monomode step index fiber

22.

Light signals passes through multimode graded index fibre due to

A.	continuous refraction	B.	total internal reflection
C.	both continuous refraction and total internal reflection	D.	diffraction

23.

Which one type of fibre is more suitable for transmission of signals in which white light is used ?

A.	mono mode step index fibre	B.	multi mode step index fibre
C.	multi mode graded index fibre	D.	single mode step index fibre

24.

Critical angle is that incident angle in denser medium for which angle of refraction is

A.	0?	B.	45?
C.	90?	D.	180?

25.

There is no noticeable boundary between core and cladding

A.	multi mode step index fibre	B.	multi mode graded index fibre
C.	single mode step index fibre	D.	all types of fibre

26.

The electrical signals change into light signals for transmission through optical fibre. A light pulse represent

A.	zero (0)	B.	One (1)
C.	both zero (0) and one (1)	D.	neither zero (0) nor one (1)

27.

A lens, which is thicker at the center and thinner at the edges is called

A.	concave lens	B.	convex lens
C.	plano convex lens	D.	plano concave lens

28.

A spectrometer is used to find

A.	wave length of light	B.	refractive index of the prism
C.	wavelength of different colours	D.	all of the above

29.

If a convex lens of focal length f is cut into two identical halves along the lens diameter the focal length of each half is

A.	f	B.	f/2
C.	2f	D.	3f/2

30.

A convex and concave lens of focal length f are in contact the focal length of the combinations will be

A.	zero	B.	f / 2
C.	2f	D.	infinite