Light Blog 3

CLASS 8 CHAPTER 16

Light
Day 3

Dear Learners,

In the previous blog, we have learned about light and reflection of light. Let me help you to recall few important points

1. Regular and Irregular reflection.
2. Real and Virtual Image.


Today, we will be learning about Characteristic of image by a plane mirror and Ray diagram for the formation of image by a plane mirror.

Happy Learning!😊

At the end of it, you will be able to:

1. tell the characteristic of image formed by plane mirror.
2. explain ray diagram for the formation of image by a plane mirror.
3. draw the ray diagram for the formation of image by a plane mirror.

But, before we start the chapter you all should read page no 252, 253 of your text book. By doing this, it will be easier for you all understand the topic well.

So, lets start the topic.........

(A) RAY DIAGRAM FOR THE FORMATION OF IMAGE BY PLANE MIRROR

To construct a ray diagram for the formation of an image follow the rules:

1. A ray of light falling on a plane mirror at 90° (perpendicular) gets reflected back from the mirror by the same path.

2. A ray of light falling on a plane mirror at any angle gets reflected from the mirror such that the angle of incidence is equal to the angle of reflection.

(Draw the diagram and also that is given in your book page 252)


(B) IMAGE OF A POINT OBJECT IN A PLANE MIRROR

1. Let us consider a point object O placed in front of a plane mirror MM'.
2. We consider two rays of light OA and OB falling on the mirror at points A and B.
3. The rays rays after reflection, get reflected along AC and BD.
4. The reflected rays appear to come from point I. 
5. The point I is the image of point object O.

(Draw the diagram, you can refer to page 253 of your text book)

(C) IMAGE OF AN EXTENDED OBJECT IN A PLANE MIRROR
1. Let us consider an object OO' placed in front of a mirror MM'.
2. Rays OA, OB start from the top of the object get reflected after striking the mirror. 
3. The reflected rays AE and BF appear to come from the point I. The point I is the image of the top of the object.
4. Rays O'C and O'D start from the lowest point of the candle get reflected after striking the mirror.
5. The reflected rays, CG and DH appear to come from point I'. The point I' is the image of the foot of the candle.
6. The II' is the image of the object OO'. 

Click on the link : https://www.youtube.com/watch?v=kspo4kU1PKo

From this diagram, we can conclude that-

The image in a plane mirror is (i) virtual, (ii) of the same size as the object,   (iii) laterally inverted, (iv) as far behind the mirror as the object is in front.

i hope the part that we have discussed above is clear to you all. Now let us move to next topic.

Home Assignment
1. Read page no 252, 253, 254.
2. Do MCQ's A-1,A-2,One word B-1,B-2 given on page 263 in your note book.