Page 40 - cbse-class-10-light-reflection-and-refraction

The optical center is used to measure all distances along the principal axis.
Distances measured in the direction of incident rays are positive, while distances
measured in the opposite direction of incident rays are negative. All measurements
taken above the principal axis are positive. As a result, the height of an object and
the height of an erect image are both positive, while all distances measured below
the principal axis are negative.

Lens Formula

The lens formula or lens equation describes the relationship between the object's
distance (u), the image's distance (v), and the focal length (f) of the lens.

1  1  1
f v u

This lens formula works for both convex and concave lenses.

Note: Things to keep in mind when using the lens formula. The known parameter
values should be used with their proper sign according to the sign convention.
During calculations, the unknown parameter should not be given a sign.

Magnification

Magnification is defined as the ratio of image size (h ) to object size (h ).
I
o

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