## Physics - Lenses

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accommodation      concave      convex      distant      focus      image      inverted      lenses      near      negative      outward      per metre      positive      retina      shape      upright      virtual
A converging lens is also known as a lens. A converging lens forms a image when the object is inside the focus. It bulges at its centre.
If the object is outside its focus, the image is real and . If the object is inside the , the image is virtual and upright.
A diverging lens is also called a lens which caves inward at its centre. It always forms a virtual, and diminished image.
The magnification of a lens is height of ÷ height of object, or object distance ÷ image distance.
For a converging lens, f is , while for a diverging lens, f is .
The power of a lens, P = 1÷f and its unit is the (m-1).
For two in contact P = P1 + P2.
Light entering the eye is brought to a focus on the . A short sighted person cannot focus clearly on objects while a long sighted person cannot focus on objects.
The power of of the eye means that the eye can focus on objects at different distances by changing the and focal length of the lens.