The distances
measured in the same direction as the
incident light are taken as positive and
those measured in the direction
opposite to the direction of incident light are taken as negative (Fig 9 2) The heights measured upwards with respect to x-axis and normal to the
Rationalised 2023-24
Ray Optics and
Optical Instruments
223
principal axis (x-axis) of the mirror/lens are taken as positive (Fig