Light

Samacheer Book Back Questions And Answers For Science Standard 7 Term 3 “Light“

I. Choose the correct option:
1. Light travels only in a _____. It is because of this property that _____ are formed
(a) Curved line, shadows
(b) Straight line, shadows
(c) Straight line, reflection
(d) Curved line and then straight line, shadows

2. Light that hits a mirror gets _____.
(a) Transmitted
(b) Reflected
(c) Absorbed
(d) Refracted

3. _____ surface reflects the light well
(a) Water
(b) Compact disc
(c) Mirror
(d) Stone

4. Light is a form of ____.
(a) Matter
(b) Energy
(c) Medium
(d) Particle

5. You can see your image in polished floors, but not in wooden table because _____.
(a) Regular reflection takes place in wooden table and irregular reflection in polished floor
(b) Regular reflection takes place in polished floor and irregular reflection in wooden table
(c) Regular reflection takes place in both polished floor and wooden table
(d) Irregular reflection takes place in both polished floor and wooden table

6. Choose the translucent substance from the following
(a) Glass
(b) Wood
(c) Water
(d) Clouds

7. Reflection occurs, when the light
(a) About to reach a surface
(b) Approaches a surface
(c) Passes through a surface
(d) None Of these

8. Which of the following is the best reflector
(a) Plastic plate
(b) Plane mirror
(c) Wall
(d) Paper

9. Sivarajan placed a meter stick in the playground at 7.00 am in the morning. How will the shadow of the stick at noon look in comparison to the one in the morning
(a) There will be no shadow
(b) The shadow will be longer and on the opposite side as the sun
(c) The shadow will be shorter and on the same side as the sun
(d) The shadow will be shorter

10. The image formed by a pinhole camera is inverted because,
(a) Light travels in straight lines
(b) Light rays become laterally inverted as they pass through a pinhole camera
(c) Light rays pass through the pinhole
(d) Light rays get reflected

11. Which of the following facts explain how shadows are formed?
(i) Light travels in straight lines
(ii) Opaque bodies do not allow light to pass through them
(iii) Reflection occurs at a smooth surfaces like mirrors
(iv) Lateral inversion happens
(a) both i and ii
(b) both i and iv
(c) both ii and iii
(d) only i

II. Fill in the blanks:
1. A plane mirror produces a _____ image
2. A _____ reflection helps us to see the objects
3. The light ray gets _____ when it falls on any polisher surface
4 Sunlight is a blend of _____ colours
5. The splitting of white light into seven colours is called _____.
6. The moon _____ sun light.
7. The sunlight can be split into its constituent colours using _____.
8. Reflection of light from rough surface is called _____ reflection

Answers:
1. Virtual and erect
2. Regular
3. Reflected
4. Seven
5. Dispersion
6. Reflects
7. Prism
8. Irregular

III. Say True or False:
1. The image of right hand in a plane mirror looks like a left hand.
2. Rainbow is formed by dispersion of which light by water drops.
3. The image formed by the plane mirror is laterally inverted, hence the image seen through the periscope is also laterally inverted.
4. We see planets because they reflect light from the sun
5. We see a book because it reflects the light that falls on its surface
6. The image formed in a pinhole camera is always inverted
7. The image formed in a pinhole camera is always the same size as the object
8. The image formed in a plane mirror is upside down
9. A plane mirror is opaque Ans.
10. A shadow is formed on the same side of the object as the source of light.
11. We are able to see things around us with the help of regular reflection
12. After passing through a prism, white light splits into a band of seven colours

Answers:
1. True
2. True
3. False (The image formed by the plane mirror is laterally inverted, hence the image seen through the periscope is virtual without lateral inversion)
4. True
5. True
6. True
7. False (The image formed in a pinhole camera is not always the same size as the object)
8. False (The image formed in a plane mirror is erect)
9. True
10. False (A shadow is formed on the opposite side of the object as the source of light)
11. True
12. True

IV. Match the following:
1. Rectilinear propagation         A. Primary source of light
2. Plane Mirror                           B. Non-luminous object
3. Fire fly                                    C. Periscope
4. The Moon                              D. Pinhole camera
5. Wide light source                  E. Spectrum of light
6. Regular reflection                  F. Luminous object
7. The sun                                 G. Penumbra
8. Band of seven colors             H. Glossy surface

Answers:
1. D
2. C
3. F
4. B
5. G
6. H
7. A
8. E

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