Light Worksheet-4

Light Worksheet-4

1. The Braille code used by blind people use dot patterns for words. How many dot patterns or characters are used for this code?

(a) 52                  (b) 63                  (c) 48                  (d) 26

2. Which of the following letters will be seen without any change in a plane mirror?

(a) S                    (b) T                    (c) L                    (d) P

3. An ideal mirror:

(a) absorbs all the amount of light incident on it

(b) refracts all the light

(c) reflects all the light

(d) none of these

4. Plane mirrors are arranged at an angle to get a number of coloured images in:

(a) Periscope                                 (b) Kaleidoscope

(c) Telescope                                 (d) Thermoscope

5. A series of fast moving still pictures can create an illusion of movement because:

(a) the eye can focus on very rapidly changing pictures

(b) eye is quicker than the brain

(c) eye can separate two images only when the interval of separation between them is one-tenth of a second

(d) the optical cortex can see through the rapidly moving images.

6. Internal reflections of light is prevented in human eye by:

(a) iris                (b) Pupil            (c) Choroid        (d) blind spot

7. For a normal eye, in case of an adult, the least distance of distinct vision is:

(a) 5 to 8 cm                                  (b) 10 to 15 cm

(c) 20 to 25 cm                             (d) 30 to 35 cm

8. The human eye part which can be used again and again for forming different images is called:

(a) Iris                (b) Pupil            (c) Cornea         (d) Retina

9. The image formed by the eye lens on the retina is:

(a) real, upright and enlarged

(b) real, upright and diminished

(c) real, inverted and diminished

(d) virtual, inverted and diminished

10. Power of accomodation of eye implies:

(a) control intensity

(b) prevent internal reflection of light

(c) change of focal length of eye lens

(d) all of these

Answer Key:

(1)-(b); (2)-(b); (3)-(c); (4)-(b); (5)-(c); (6)-(c); (7)-(c); (8)-(d); (9)-(c); (10)-(c)