NCERT Class VIII Science Solutions: Chapter 16-Light Part 1

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Question 1:

Suppose you are in a dark room. Can you see objects in the room? Can you see objects outside the room? Explain.

Answer:

We can see any object, when light reflected by that object reaches to our eyes. But in the dark room, no light is reflected by the object. Hence, we are not able to see the objects in dark room. But if there is light outside the room, we can see the objects lying out there.

Question 2:

Differentiate between regular and diffused reflection. Does diffused reflection mean the failure of the laws of reflection?

Answer:

Differentiate between Regular and Diffused Reflection.
Differentiate between regular and diffused reflection.

S. No.

Regular Reflection

Diffused Reflection

1.

It takes place from a smooth place

It takes place from a rough surface

2.

Reflected rays moves in a particular direction

Reflected rays scattered in random directions

3.

Example: Reflection by plane mirror

Reflection by road surface

Result for Differentiate between regular and diffused reflection

Differentiate between Regular and Diffused Reflection

Result for Differentiate between regular and diffused reflection

Question 3:

Mention against each of the following whether regular or diffused reflection will take place when a beam of light strikes. Justify your answer in each case.

  1. Polished wooden table

  2. Chalk powder

  3. Cardboard surface

  4. Marble floor with water spread over it

  5. Mirror

  6. Piece of paper

Answer:

A polished wooden table is an example of smooth surface. So, when a beam of light reflects from it, a regular reflection will take place.

As showing in images is a polished wooden table

Polished Wooden Table

As showing in images is a polished wooden table

Chalk powder has irregular surface. So, when a beam of light reflects from it, a diffused reflection will take place.

Image result for chalk powder

Chalk Powder

Image result for chalk powder

A cardboard has irregular surface. So, when a beam of light reflects from it, a diffused reflection will take place.

Image result for cardboard

Cardboard

Image result for cardboard

A marble floor with water spread over it provides a smooth surface. So, when a beam of light reflects from it, a regular reflection will take place.

Image result for A marble floor with water spread over

Marble Floor with Water Spread Over

Image result for A marble floor with water spread over

A mirror has a smooth surface. So, when a beam of light reflects from it, a regular reflection will take place.

Image result for mirror

Mirror

Image result for mirror

A piece of paper may appear smooth but it has many minor irregularities. So, when a beam of light reflects from it, a diffused reflection will take place.

Image result for piece of paper

Piece of Paper

Image result for piece of paper