# Light: Reflection and Refraction

## Formation of Image by convex lens:

There are six possibilities of position of object in the case of convex lens:-

1. Object at infinity
2. Object beyond centre of curvature, C
3. Object at centre of curvature, C
4. Object between centre of curvature, C and principal focus, F
5. Object at principal focus, F
6. Object between principal focus, F and optical centre, O

### (a) Object at infinity:-

Convex lens converge parallel rays coming from objet at infinity and a highly diminished - point sized, real and inverted image is formed at principal focus F2.

Position of image: At F2

Nature of image: Real and inverted

Size of image: Point sized, highly diminished.

#### (b) Object beyond centre of curvature, C1 or 2F1:-

A diminished, real and inverted image is formed between principal focus, F2 and centre of curvature, C2 at the opposite side when an object is placed beyond C1 of a convex lens.

Position of image: Between 2F2 and F2

Nature of image: Real and inverted

Size of image: Diminished.

##### (c) Object at centre of curvature, C1 or 2F1:

A same sized, real and inverted image is formed at centre of curvature, C2 when object is placed at centre of curvature, C1 of a convex lens.

Position of image: At 2F2

Nature of image: Real and inverted

Size of image: Same sized.

###### (d) Object between centre of curvature, C1 and principal focus, F1:

An enlarged, real and inverted image is formed beyond centre of curvature, C2 when an object is placed between centre of curvature, C1 and principal focus, F1 of a convex lens.

Position of image: Beyond 2F2

Nature of image: Real and inverted

Size of image: Enlarged

(e) Object at principal focus, F1:-

An infinitely large, real and inverted image is formed at infinity when object is placed at principal focus, F1 of a convex lens.

Position of image: At infinity

Nature of image: Real and inverted

Size of image: Highly enlarged

(f) Between principal focus, F1 and optical centre, O:-

A virtual, erect and enlarged image is formed at the same side of lens, when an object is placed between principal focus, F1 and optical centre, O of a convex lens.

Position of image: Beyond 2F1

Nature of image: Virtual and erect

Size of image: Enlarged.

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