Question
Give the important rules of the new cartesian sign convention followed for refraction of light through spherical lenses.
Solution
Rules of new cartesian sign convention:
(i) The focal length of a convex lens is positive and that of a concave lens is negative.
(ii) Object distance u is always negative as it is on the left side of the mirror.
(iii) The distance of real image is positive and that of virtual image is negative.
(iv) The height of the object h is always positive. Height h', of virtual and erect image is positive and that of real and inverted image is negative.
(v) The linear magnification, m = h'/h is positive for a virtual image and negative for a real image.
