SCIENCE -- CH- LIGHT SHADOWS AND REFLECTION (NOTEBOOK AND WORKBOOK EXERCISE)

 

CH- LIGHT SHADOWS AND REFLECTION (NOTEBOOK AND WORKBOOK EXERCISE)

NEW WORDS

inverted

diminished

non-luminous

translucent

lateral

New terms

diminished- to reduce

emit-to give out light

Q.1.Answer the following questions in one word or a sentence.

a. Write any two artificial sources of light.

Ans. Bulb, torch, tube-light are artificial sources of light.

b. How are we able to see non-luminous objects? 

Ans. Non-luminous objects can only be seen if they reflect light from a luminous source. For example, Moon does not have its own light. It reflects the light coming from the Sun.

c. When does a solar eclipse occur?

Ans. Solar eclipse occurs only on a new Moon day.

Answer the following questions in short. 

a. List the conditions necessary for the formation of a shadow

Ans.A shadow is formed only when light is blocked by an opaque object. 

• The colour of the shadow is always black irrespective of the colour of the object. 

• The shape of the shadow may or may not be the same as the toy. 

• The shadow can be formed only on a screen. 

• The size of the shadow depends on the shape and size of the object and the position of the source of light.

b. We are not able to see things behind a wall. What does this fact tell us about light? 

Ans.Those materials which do not allow any light to pass through them are called opaque materials. They absorb all the light radiations falling on them so We are not able to see things behind a wall.

c. Differentiate between luminous and non-luminous objects. 

Luminous Objects-- 

1. Any object that emits its own light is called as luminous. 
2. For example Sun, tube-light, burning candle, etc

Non luminous objects--  

1.Objects that do not emit their own light are said to be non-luminous. 

2.For example Moon, the Earth, table, chair, tree, etc

d. List the characteristics of an image formed in a plane mirror.

• The image is of the same size and same colour as that of the object. 

• The image formed is laterally inverted.

7. Give reason. 

a. A transparent object cannot cast a shadow. 

Ans. When the glass plate(a transparent object) was placed no shadow was formed as most of the light passed through it.

8. Answer the following questions in detail. 

a. Differentiate between transparent, translucent and opaque objects. 

1. Transparent materials Those materials which allow all the light to pass through them are called transparent materials. For example – water, air, glass, etc.

2. Translucent Materials Those materials which allow some of the light to pass through them are called translucent materials. For example – butter paper, oiled paper, molten wax, frosted glass, etc.

 3. Opaque Materials Those materials which do not allow any light to pass through them are called opaque materials. They absorb all the light radiations falling on them. For example – Book, wall, wood, cardboard sheet, etc

b. State the difference between a solar eclipse and lunar eclipse. When do they occur? 

Solar eclipse – On some days, the Moon comes exactly in between the Sun and the Earth and the shadow of the Moon falls on the Earth. This is called a Solar eclipse. Solar eclipse occurs only on a new Moon day. Draw diagram of solar eclpise

 Lunar eclipse – The Earth moves around the Sun and the Moon moves around the Earth. When the Earth comes in between the Sun and the Moon and all three are in the same straight line, the shadow of the Earth falls on the Moon and the view of the Moon gets partially or completely blocked for some time. This eclipsing of the Moon is known as lunar eclipse. A lunar eclipse occurs on a Full Moon Day. 

draw diagram of lunar eclipse

c. What is lateral inversion? Mention one of its uses

In lateral inversion the reflection of image always reverses from left to right. The best example of lateral inversion can be seen in the word AMBULANCE written on the vehicle. The word is laterally inverted so that, when the driver of a vehicle in front looks into his rear view mirror, he can make out the word quickly and give way.

Attempt Q.10,11 by your own 

10. Diagram based questions: (Please see the diagram from textbook and complete the following questions also draw the diagrams in notebook.)

a. Observe the diagram and attempt the following questions: i. In which of the following cases will the observer be able to see the flame of the candle? Why?

 ii. State the property of light depicted in the above case. 162 

b. Draw the image of the word ‘SCIENCE’ as seen in the mirror. Also identify and name the phenomenon of light seen in this case. Explain the characteristics of the image formed. 

11. HOTS ( Higher Order Thinking Skills) a. We observe a clear image of ourselves on the surface of a clean water lake. b. Why is your shadow the longest at noon and the shortest during the morning and evening?

LINK FOR WORKBOOK EXERCISE--------CLICK THE LINK BELOW

https://drive.google.com/file/d/11SDg9PvtoJc_MTzxOXtwRFcwnF965EIc/view?usp=sharing