Light: Image Formation by Convex Lens
These notes are based on the chapter Light: Reflection and Refraction from class 10 science NCERT book and CBSE syllabus
There are six possibilities of position of object in the case of convex lens:
- Object at Infinity
- Beyond C
- Between C and F
- Object at C
- Object at F
- Between F and O
Object at infinity
Fig: 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.
Properties of Image: Image is highly diminished, real and inverted.
Object beyond C1 or 2F1
Fig: Object Beyond 2F
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.
Properties of Image: Image is diminished, real and inverted.
Object at C or 2F1
Fig: Object at 2F
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.
Properties of Image: Image is same size as object, real and inverted.
Object between C and F
Fig: Object between 2F and F
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.
Properties of Image: Image is enlarged, real and inverted.
Object at Focus F1
Fig: Object at F
An infinitely large, real and inverted image is formed at infinity when object is placed at principal focus, F1 of a convex lens.
Properties of Image: Image is highly enlarged, real and inverted.
Between F1 and O
Fig: Object between F and O
Properties of Image: Image is enlarged, virtual and erect.
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.
Summary of Image Formation
- Object at Infinity: Image is formed at focus. Image is real, inverted and highly diminished in size.
- Beyond C: Image is formed between F2 and 2F2. Image is real, inverted and smaller than object.
- Between C and F: Image is formed beyond C2 or 2F2. Image is real, inverted and larger than object.
- At C: Image is formed at 2F2 or C2. Image is real, inverted and of same size as object.
- At F: Image is formed at infinity. Image is real, inverted and highly enlarged.
- Between F and O: Image is formed on 2F1. Image is virtual, erect and larger than object.
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