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| Formation of Image by a Concave Lens |
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| The following rays are considered while constructing ray diagrams for locating the images formed by a concave lens for the various position of the object. |
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 An incident ray of light coming from the object parallel to the principal axis of a concave lens after refraction appears to come from its focus. |
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An incident ray of light passing through the optical center comes out of the
lens without any deviation. |
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 A concave lens always gives a virtual, erect and diminished image whatever may be the position of the object. |
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| Let us now draw ray diagrams to show the position of the images when the object is placed |
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 at infinity and |
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 between O and F1 and |
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 any position between infinity and O. |
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| When the Object is at Infinity |
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| The image is - |
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 formed at F1 |
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 erect |
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 virtual |
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 diminished |
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| When the Object is Placed between O and F1 |
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 |
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| The image is - |
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 formed between O and F1 |
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 erect |
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 virtual |
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 diminished |
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| When the Object is placed at any Position between O and infinity |
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 |
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| The image is - |
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 formed between O and F1 |
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 erect |
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 virtual |
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 diminished |
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| It is used |
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 in spectacles for correcting myopia. |
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 along with convex lens it is used to overcome defects like chromatic aberration and spherical aberration (the failure of rays to converge at one focus because of a defect in a lens or mirror). |
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