Textbook Solutions: Light, Shadow and Reflections | Eureka Plus Class 6: Book Solutions, Notes & Worksheets PDF Download

I. Tick (✔) the true sentences and correct the false ones.

1.
Ans: True

2.
Ans: False
Light travels at a speed of 3,00,000 km per second.

3.
Ans: False
Light travels at a speed of 3,00,000 km per second.

4.
Ans: True

5.
Ans: True

6.
Ans: True

7.
Ans: True

8.
Ans: False
A solar eclipse occurs when the moon comes between the sun and the Earth.

II. Answer the following questions in one sentence. 

1.
Ans: A luminous object is one that produces light of its own.

2.
Ans: Natural: The sun, Human-made: Electric bulbs.

3.
Ans: An illuminated object does not produce light but appears bright because light falls on it.

4.
Ans: Solar energy is the energy from the sun, which includes light and heat.

5.
Ans: One light year is the distance traveled by light in one year, which is about 3,00,000 kilometers per second.  

6.
Ans: Opaque objects form clear shadows.  

7.
Ans: A luminous source of light, an opaque object, and a surface or a screen to capture the shadow.  

8.
Ans: A beam of light travels in straight lines, known as rays, and the rays in a beam of light are normally parallel. 

III. Do as directed.

1. Explain the following with simple line diagrams and labels.
(a).
Ans: Diagram with parallel lines representing rays of light in a beam  

(b).
Ans: Diagram showing incident and reflected rays with arrow

(c).
Ans: Diagram showing scattered rays in different directions

(d).
Ans: Diagram showing an object, a pinhole, and an inverted image formed on the opposite side

2. 
Ans:

IV. Answer the following questions in about four to five sentences. Include simple diagrams wherever necessary. 

1.
Ans: A luminous object produces its own light, like the sun or a lighted candle, while an illuminated object does not produce light but appears bright because light falls on it, such as the Earth being illuminated by sunlight.

2.
Ans: The sun is crucial because it provides both light and heat energy, sustaining life on Earth. Plants use sunlight for photosynthesis, and all living things, directly or indirectly, depend on the food made by plants.

3.
Ans: During a solar eclipse, the moon comes between the sun and the Earth, casting a shadow on certain regions. In a total solar eclipse, the sun appears fully covered by the moon, creating darkness. In a partial solar eclipse, only some regions experience the faint shadow of the moon. (Diagram illustrating the alignment of the sun, Earth, and moon)

4.
Ans: When the shadow of the Earth falls on the moon, it causes a lunar eclipse. This occurs when the Earth comes between the sun and the moon, and the moon passes through the Earth's shadow. (Diagram depicting the alignment of the sun, Earth, and moon during a lunar eclipse).

5.
Ans: A plane mirror has a smooth, polished surface, and when light falls on it, the reflected rays remain parallel, forming a clear image. In contrast, a rough floor reflects light in various directions, causing scattered rays and preventing the formation of a clear image. (Diagram comparing the reflection on a plane mirror and a rough floor)

Think and answer

I. 
Ans:
The sun and the moon are luminous natural objects. The sun is a source of light. It produces small amounts of heat and light energy all the time. All the energy produced by the sun reaches our Earth, but it takes about an hour to reach the Earth. Light from the sun illuminates a part of the Earth at any given time. It also illuminates the moon, which is why the moon appears bright. Because of the heat from the sun, the Earth is warm and has life, In contrast, sunlight plays a crucial role in supporting life on Earth.

II.  

1.
Ans: Yes, the object is opaque because it does not allow light to pass through, which is why it casts a shadow.

2.
Ans: The ground or any surface on which the shadow is cast acts as the screen that captures the shadow.

3.
Ans: Yes, the position of the sun does affect the shadow. As the sun's position in the sky changes throughout the day, the length and direction of the shadow also change.

4.
Ans: Yes, the shape of the object affects the outline and form of the shadow. However, since the shadow is a two-dimensional projection, some three-dimensional features may not be distinctly represented.