### Light Reﬂection and Refraction

1.The bending of a beam of light when it passes obliquely from one medium to another is known as       .

A.  reflection

B.  refraction

C.  dispersion

D.  deviation

2.The part of the lens through which the ray of light passes without suffering deviation is called                .

A.  optical centre

B.  focus

C.  centre of curvature

D.  pole

3. Convex lens always gives a real image if the object is situated beyond               .

A.  optical centre

B.  centre of curvature

C.  Focus

4. Parallel rays of light entering a convex lens always converge at              .

A.  centre of curvature

B.  the principal focus

C.  optical centre

D.  the focal plane

5. Where should an object be placed so that a real and inverted image of the same size is obtained, using a convex lens?

A.  Between O and F

B.  At F

C.  At 2 F

D.  At infinity

6. SI unit of the power of a lens is

A.      dioptre

B.      cm

C.      metre

D.    watt

7.  1 D is the power of the lens of focal length of

A.  10 cm

B.  100 cm

C.  1/ 10 cm

D.  1/100 cm

8. In a simple microscope lens used is              .

A.  biconvex

B.  biconcave

C.  plano convex

D.  cylindrical

9. Reciprocal of focal length in metres is known as the     of a lens.

A. focus

B. power

C. power of accommodation

D. far point

10. A convex lens is called             .

A. converging lens

B. diverging lens

C. both converging and diverging lens

D. refracting lens

11. A positive magnification greater than unity indicates                .

A. real image

B. virtual image

C. neither real not virtual image

D. distorted image

12. The power of a convex lens of focal length 50 cm is    .

A. + 2D

B. - 2D

C.  50 D

D.  - 5D

13            The focal length of a lens whose power is -1.5 D is

A.             -66.66 cm

B.      + 1.5 m

C.   + 66.66 cm

D.    -1.5 m

14. Real images formed by single convex lenses are always          .

A.  on the same side of the lens as the object

B.  Inverted

C.  Erect

D.  smaller than the object

15. An object is placed 12 cm from a convex lens whose focal length is 10 cm. The image must be.

A.  virtual and enlarged

B.  virtual and reduced in size

C.  real and reduced in size

D.  real and enlarged

16. When a person uses a convex lens as a simple magnifying glass, the object must be placed at a distance.

A.  less than one focal length

B.  more than one focal length

C.  less than twice the focal length

D.  more than twice the focal length

17. The image produced by a concave lens is       .

A.  always virtual and enlarged

B.  always virtual and reduced in size

C.  always real

D.  sometimes real, sometimes virtual

18.  A virtual image is formed by                .

A.  a slide projector in a cinema hall

B.  the ordinary camera

C.  a simple microscope

D.  Telescope

19.  An object is placed 25 cm from a convex lens whose focal length is 10 cm. The image distance is         cm.

A.  50 cm

B.  16.66 cm

C.  6.66 cm

4.  10 cm

20. The least distance of distinct vision is               .

A.  25 cm

C.  25 m

C.  0.25 cm

D.  2.5 m