PHYSICS 10 CH10 LIGHT - TOPIC 1.07 -1.09

THE PHYSICS CAFE                                                   

CHAPTER TEN - LIGHT - REFLECTION AND REFRACTION

1.07 Image Formation in Concave and Convex Mirror**                                               

Rules for Image Formation in both Concave and Convex mirror:

1. Always face the mirror towards left side.

2. Always place the object left side of mirror.

3. Take two light rays from the head of object. One parallel to principal axis and second incident at pole.

4. Incident light ray parallel to principal axis will always pass through focus.

5. Incident light ray falling at pole will always reflected at the angle equal to incidence angle.

6. Image will be formed at the point where both the reflected light ray meets. The distance of this point from the pole is called Position of image

7. If both reflected light ray meets actually then the image formed will be Real image and if both reflected light ray don’t meet actually, then extend them backside of mirror and then the image will be formed at the point where extended rays meet and this type of image is called Virtual image.

8. Hint: The arrow head represents the head of the object/image and foot will always lie on principle axis.

9.   Size of the image is told as compared to object like image formed is point sized, small sized, same sized, large sized, very large sized.

Hint: To draw reflected ray, place a point just below the image at a distance equal to height of the object. Now pass the reflected light ray from this point.

 If the image’s head is upside is called Erect image

 If the image’s head is downside is called Inverted image

Hint: Real Image: Real image will be in front of the mirror, that why we can touch it because reflected light ray actually meets there and can see it on screen (screen means it can be any white color smooth material) 

Virtual Image: Virtual image will be in back side of the mirror, that why we can touch it because reflected light ray don’t cross the mirror and can’t see it on screen.

To see image formation video lecture click here…

1.08 Checking of Position, Nature and Size of Image*                                                 

For concave mirror:

We have six positions to place the object in front of concave mirror. If object is placed at infinity, light rays come parallel to principal axis and after reflection by mirror meets at focus, thus image will be formed at focus (F). Now check in your notebook if object is placed at infinity and the image is formed at focus, then it is correct otherwise find mistake and re-draw. 

Hint: Dimensions must be proper for correct result.

Position of the object	Position of the image	Size of the image	Nature of the image
At infinity	At F	Point sized	Real and inverted
b/w infinity and C (beyond C)	b/w C and F	Small sized	Real and inverted
At C	At C	Same sized	Real and inverted
b/w C and F	b/w infinity and C (beyond C)	Large sized	Real and inverted
At F	At infinity	Very large sized	Real and inverted

 From the above table we can see as we move object one position towards the mirror from infinity to between infinity and C, the image moves one position away from the mirror from focus to between C and F and so on

For Convex mirror:

We have only two positions to place the object in front of convex mirror.

Position of the object	Position of the image	Size of the image	Nature of the image
At infinity	At F	Point sized	Virtual and Erect
b/w infinity and P	b/w P and F	Small sized	Virtual and Erect

Hint: Convex mirror always forms small sized, erect and virtual images.

 

1.09 Uses of Concave and Convex Mirror in Daily Life*                                                

 Uses of Concave mirrors:

1. To get powerful parallel beam of light rays by placing bulb at focus. In torches, search lights, vehicle headlights etc.
2. To see large image. In saving mirrors to see a large image of face and by dentist to see the large image of teeth.
3. To concentrate sunlight at a small region to produce heat in solar furnaces. 

Uses of Convex mirrors:

1. To get erect image.
2. To get wider field of view. They are used as rear view (wing) mirrors in vehicles that enables driver to view large area and erect image.

Click here for download.. Rules for image formation, checking and uses of concave and convex mirrors 1.07 - 1.09
Click here for download.. Spherical mirrors, identification and image formation rules 1.05 - 1.06
Click here for download.. Reflection of light, laws and properties 1.01 -  1.04
Click here for download.. NCERT SCIENCE 10 CH10 - IN TEXT QUESTION ANSWER

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