Entry Test MCQ :: Optical Instruments

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A lens which converges a beam of parallel rays to a point is called

A.	diverging (or concave) lens	B.	converging (or convex) lens
C.	plano concave lens	D.	plano convex lens

A point where the incident parallel rays of light converge or appear to diverge after passing through a lens is called

A.	center of curvature	B.	focus
C.	optical center	D.	aperture

The diameter of a lens is called

A.	focal length	B.	principal axis
C.	aperture	D.	radius of curvature

In going form a denser to rarer medium a ray of light is

A.	undeviated	B.	bent away form the normal
C.	bent towards the normal	D.	polarized

Unit of power of a lens is

A.	meter	B.	watt
C.	dioptre	D.	horsepower

Dioptre power of an concave lens of 10 cm focal length is

A.	10 dioptre	B.	10 dioptre
C.	1 / 10 dioptre	D.	1 / 10 dioptre

The power of a concave lens is

A.	real	B.	virtual
C.	positive	D.	negative

The minimum distance between an object and its real image in a convex lens is

A.	2 f	B.	2.5 f
C.	3f	D.	4f

If an object is placed away from 2f of a converging lens then the image will be

A.	real and erect	B.	virtual and erect
C.	real and inverted	D.	virtual

10.

A convex lens gives a virtual image only when the objects lies

A.	between principal focus and center of curvature	B.	beyond 2 f
C.	at the principal focus	D.	between principal focus and optical center