## Samacheer Kalvi 7th Science Term 3 Unit 1 Book Back Questions and Answers:

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### Samacheer Kalvi 7th Science Book Back Chapter 1 Term 3 Solutions Guide PDF:

TN State Board Class 7th Science Subject Term 3 Unit 1 one mark and two mark solutions guide PDF available below.

#### Unit 1 – Light

I. Choose the correct option:

1. Light travels only in a ______. It is because of this property that ______.
(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) partical

5. You can see your image on polished floors, but not on wooden tables because ______
(a) regular reflection takes place on wooden tables and irregular reflection on the polished floor
(b) regular reflection takes place on the polished floor and irregular reflection on the wooden table
(c) regular reflection takes place on both polished floors and wooden table
(d) irregular reflection takes place in both polished floors and wooden table
Answer: (b) regular reflection takes place on the polished floors and irregular reflection on 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
Answer: (a) light travels in straight lines

11. Which of the following facts explains how shadows are formed?
(a) Light travels in straight lines
(b) Opaque bodies do not allow light to pass through them
(c) Reflection occurs on a smooth surface like mirrors
(d) Lateral inversion happens
(a) both A and B
(b) both A and D
(c) both B and C
(d) only A
Answer: (a) both A and B

#### 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 _________ sunlight.
7. The sunlight can be split into its constituent colours using _________
8. The reflection of light from a rough surface is called _________ reflection

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 the right hand in a plane mirror looks like a left hand.

2. Rainbow is formed by the dispersion of 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
Correct statement: The image formed by the plane mirror is laterally inverted, hence the image seen through the periscope is This is because, in the periscope, the image is reflected by two mirrors.

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 satne size as the object

8. The image formed in a plane mirror is upside down
Correct statement: The image formed in a plane mirror is erect.

9. A plane mirror is opaque Ans.

10. A shadow is formed on the same side of the object as the source of light.
Correct statement: A shadow is formed on the 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.

### IV. Match the following:

 1 Rectilinear propagation The primary source of light 2 Rectilinear propagation Non-luminous object 3 Plane Mirror Firefly Periscope 4 The Moon Pinhole camera 5 Wide light source Spectrum of light 6 Regular reflection luminous object 7 The sun Penumbra 8 Band of seven colors Glossy surface