Entry Test MCQ :: Optical Instruments

1.  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

2.  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

3.  The diameter of a lens is called
A. focal length B. principal axis
C. aperture D. radius of curvature

4.  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

5.  Unit of power of a lens is
A. meter B. watt
C. dioptre D. horsepower

6.  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

7.  The power of a concave lens is
A. real B. virtual
C. positive D. negative

8.  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

9.  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

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