AP 7th Class Science Bits Chapter 8 Wonders of Light with Answers

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AP 7th Class Science Bits Chapter 8 Wonders of Light with Answers

I. Multiple Choice Questions

Choose the correct answer and write its letters in the brackets.

1. This is not a natural source of light.
A) sun
B) stars
C) moon
D) none
Answer:
C) moon

2. Example to human involvement is needed to release light
A) sun
B) stars
C) candle
D) none
Answer:
C) candle

3. Light rays which travel from a source moving in different directions are called as of light rays.
A) parallel
B) converge
C) diverge
D) B and C
Answer:
C) diverge

4. Which of the following does not give regular reflection?
A) mirror
B) cloth
C) new steel plate
D) polished marble
Answer:
B) cloth

5. In case of irregular reflection images cure
A) not clear
B) cannot form
C) clear
D) A & B
Answer:
D) A & B

6. These are in the same plane.
i. The incident ray
ii. normal to the surface
iii. The reflected ray
A) i,ii
B) i,iii
C) ii, iii
D) i,ii,iii
Answer:
D) i,ii,iii

7. Angle between normal and the incident ray
A) angle of incidence
B) angle of reflection
C) angle of vision
D) A & B
Answer:
A) angle of incidence

8. Which of the following is not a characteristic of the image of the plane mirror?
A) Object distance is equal to image distance.
B) Size of the object is equal to size of the image.
C) The image formed is always real and erect.
D) Laterally inverted image is formed.
Answer:
C) The image formed is always real and erect.

9. The distance of the object from the mirror is …………….. the distance of image from the mirror.
A) is equal to
B) is greater than to
C) is less than to
D) A & C
Answer:
A) is equal to

10. The size of image is not equal to that of the object in any situation.
A) plane mirror
B) convex mirror
C) concave mirror
D) none
Answer:
B) convex mirror

11. The distance of the image from the mirror is called
A) Image distance
B) Object distance
C) Normal
D) None
Answer:
A) Image distance

12. This type of image can catch on the screen
A) real
B) virtual
C) both
D) none
Answer:
A) real

13. Image formed by a plane mirror
A) erect & real
B) inverted & virtual
C) erect & virtual
D) inverted & real
Answer:
C) erect & virtual

14. No. of images formed when the angle between two plane mirrors is 60°
A) 4
B) 5
C) 6
D) 7
Answer:
B) 5

15. No. of images formed when the angle between two plane mirrors is 90°
A) 4
B) 2
C) 1
D) 3
Answer:
D) 3

16. No. of images formed when the angle between two plane mirrors is 0°
A) infinity
B) 5
C) 6
D) 0
Answer:
A) infinity

17. No. of images formed is 1, then the angle between two plane mirrors is
A) 0°
B) 90°
C) 180°
D) 360°
Answer:
C) 180°

18. The instrument which is used in submarines to see the objects or persons above the water level.
A) microscope
B) telescope
C) kaleidoscope
D) periscope
Answer:
D) periscope

19. Angle between two plane mirrors in periscope is
A) 0°
B) 90°
C) 180°
D) 360°
Answer:
A) 0°

20. The steel spoon can act as …
A) plane mirror
B) convex mirror
C) concave mirror
D) B & C
Answer:
D) B & C

21. The mirror forms all types of images
A) plane mirror
B) convex mirror
C) concave mirror
D) B & C
Answer:
C) concave mirror

22. The mirror is used as rear view mirror
A) plane mirror
B) convex mirror
C) concave mirror
D) B & C
Answer:
B) convex mirror

23. Which rule we should follow to protect eyes while watching TV or computer?
A) 20-20-20
B) 40-4-40
C) 10-10-10
D) 12-12-12
Answer:
A) 20-20-20

24. Which light is not dangerous to our eye?
A) yellow
B) red
C) blue
D) violet
Answer:
A) yellow

25. Which colour of light is composition of all colours?
A) yellow
B) red
C) blue
D) white
Answer:
D) white

II. Fill in the blanks

1. Light is a form of ………………. that helps us to see all the things around us.
2. Light comes from different objects called ………………. .
3. Objects that emit light are known as ………………. .
4. Sources that release light artificially [with human involvement] are called ………………. sources of light or artificial sources of light.
5. ………………. source emit light on their own.
6. The direction or path along which light travels is called ………………. .
7. The straight line indicates the of light and arrow mark indicates the ………………. of light from the source.
8. A bundle of light rays are called ………………. of light rays.
9. Light rays which travel parallel to each other are called ………………. of light rays.
10. Light rays which travel from different directions to meet at a point are called as ………………. of light rays.
11. Light rays which travel from a source moving in different directions are called as ………………. of light rays.
12. The process of bouncing back of light rays into the same medium after falling on a smooth or rotigh surface from the light source is called ………………. .
13. Objects are visible only when ………………. falls on the objects and bounces back to the eye.
14. Light rays from the sun fall on the mirror and bounced back and formed a spot of light on the wall. It is the image of ………………. .
15. The light rays that fall on the objects are called ………………. .
16. The light rays that bounce back from the objects are called ………………. .
17. Reflection from a ………………. surface is called regular reflection.
18. Reflection from an irregular or uneven surface is called ………………. reflection.
19. Clear images are formed in case of ………………. reflection.
20. Angle of ………………. is equal to Angle of reflection.
21. Incident and reflected rays are on either side of ………………. .
22. The angle made by incident ray with the normal is called ………………. .
23. The angle made by the reflected ray with the ………………. is called the angle of reflection.
24. The distance of the object from the mirror is called ………………. .
25. The distance of the image from the is called image distance.
26. When you are eating food with right hand it appears to be eating with left hand. This characteristic is called ………………. .
27. The image which cannot catch on the screen is called ………………. .
28. Plane mirror forms ………………. image.
29. The relation between number of images formed and the angle between two plane mirrors is ………………. .
30 . ………………. is an instrument used in submarines to see the objects or persons above the water level.
31. ………………. mirror reflect the light in different directions.
32. ………………. mirror reflect the light to one point.
33. A ………………. mirror forms real and virtual images, erect and inverted images, smaller, same size and bigger images depending on the position of object infront of it.
34. Ophthalmoscope is fitted with a ………………. mirror having a small hole near its center.
35. Dentists also use ………………. mirrors to get a bigger image of the teeth.
36. ………………. mirrors are used in head lights of the vehicles.
37. A piece of glass or any other transparent material with curved sides is called ………………. .
38. Lens which is thick in center and thin at the edges is called ………………. lens.
39. Lens which is thin in the centre and thick at the edges is called ………………. lens.
40. ………………. light has been proven effective in protecting retina than blue light which causes damage to retina.
41. Splitting of white light into seven colours is called ………………. .
Answer:

energy
sources of light
sources of light
man made
natural
a ray of light
path, direction
beam
parallel beam
Converging beam
Diverging beam
reflection of light
Light
sun
incident rays
reflected rays
smooth and shiny
irregular or diffused
regular
incidence
normal
angle of incidence
normal
object distance
mirror
lateral inversion
virtual image
virtual
360°/θ -1
periscope
convex
concave
concave
concave
concave
concave
a lens
convex
concave
Yellow
dispersion

III. Match the following

Group – A	Group – B
1) Natural source	a. cloth
2) Artificial source	b. steel plate
3) Regular reflection	c. star
4) Irregular reflection	d. candle

Answer:

Group – A	Group – B
1) Natural source	c. star
2) Artificial source	d. candle
3) Regular reflection	b. steel plate
4) Irregular reflection	a. cloth

Group – A	Group – B
1) Convex mirror	a. make up
2) Concave mirror	b. ENT doctor
3) Plane mirror	c. magnifier
4) Convex lens	d. rear view

Answer:

Group – A	Group – B
1) Convex mirror	d. rear view
2) Concave mirror	b. ENT doctor
3) Plane mirror	a. make up
4) Convex lens	c. magnifier

Group – A	Group – B
1) Periscope	a. concave mirror
2) Ophthalmoscope	b. convex mirror
3) Road safety	c. convex lens
4) Telescope	d. plane mirror

Answer:

Group – A	Group – B
1) Periscope	d. plane mirror
2) Ophthalmoscope	a. concave mirror
3) Road safety	b. convex mirror
4) Telescope	c. convex lens

Group – A	Group – B
1) Convex mirror	a. inwards curve
2) Concave mirror	b. outwards curve
3) Plane mirror	c. thick at middle
4) Convex lens	d. plane surface
5) Concave lens	e. thin at middle

Answer:

Group – A	Group – B
1) Convex mirror	b. outwards curve
2) Concave mirror	a. inwards curve
3) Plane mirror	d. plane surface
4) Convex lens	c. thick at middle
5) Concave lens	e. thin at middle

Group – A	Group – B
1) Virtual image	a. pass through one point
2) Real image	b. bundle of rays
3) Ray	c. caught on the screen
4) Beam	d. seen in the mirror
5) Converging	e. path of light

Answer:

Group – A	Group – B
1) Virtual image	d. seen in the mirror
2) Real image	c. caught on the screen
3) Ray	e. path of light
4) Beam	b. bundle of rays
5) Converging	a. pass through one point

Group – A	Group – B
1) Incident angle	a. perpendicular line to surface
2) Reflecting angle	b. angle of incidence angle of reflection
3) Normal	c. angle between normal and reflected ray
4) First law of reflection	d. normal, incident ray, reflected ray are in one plane
5) Second law of reflection	e. angle between normal and incident ray

Answer:

Group – A	Group – B
1) Incident angle	e. angle between normal and incident ray
2) Reflecting angle	c. angle between normal and reflected ray
3) Normal	a. perpendicular line to surface
4) First law of reflection	b. angle of incidence angle of reflection
5) Second law of reflection	d. normal, incident ray, reflected ray are in one plane

Group – A	Group – B
1) Convex mirror	a. converges
2) Concave mirror	b. diverges
3) Plane mirror	c. parallel rays
4) Sun	d. irregular reflection
5) Thermocol sheet	e. regular reflection

Answer:

Group – A	Group – B
1) Convex mirror	b. diverges
2) Concave mirror	a. converges
3) Plane mirror	e. regular reflection
4) Sun	c. parallel rays
5) Thermocol sheet	d. irregular reflection