Answer:
Spherical lenses are made by combining two spherical transparent surfaces. There are two kinds of spherical lenses in general. Convex lenses are made by joining two spherical surfaces that bulge outward, whereas concave lenses are made by joining two spherical surfaces that curve inward.
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Convex lens |
Concave lens |
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1 |
A convex lens is thicker in the middle and thinner at the edges. |
A concave lens is thinner in the middle and thicker at the edges. |
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2 |
Positive focal Length |
Negative focal Length |
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3 |
It converges the incident rays towards the principal axis |
It diverges the incident rays away from the principal axis. |
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4 |
Used in the camera, focus sunlight, overhead projector, projector microscope, simple telescope, magnifying glasses, etc. It is also used for the correction of the problem in long sight. |
Used in glasses, some telescopes, spy holes in the doors, etc. It is also used for the correction of the problem in short sight |
