Cartesian sign convention:

Cartesian sign convention:

Introduction: In order to understand the formation of images due to reflection from the mirror, it is convenient to use some sign conventions. The sign convention helps us to determine the position of the object as well as the image.

Cartesian sign convention

From the figure above it is clear that,

1) All the distances are measured from the optical center of the mirror.

2) The distance measured left of the mirror is always taken as negative whia le the distance measured on the right side of the mirror is taken as Positive.

3) Distance measured above the principal axis is taken as Positive while those measured below the principal axis are taken as negative.

4) Incident ray should always travel from left to right.

Note: Distance is always measured from the pole to the object or image.

You can understand it in another way.

1) The distance measured in the direction opposite to that of the incident ray is always taken as negative.

2) The distance measured in a direction similar to that of the incident ray is always taken as positive.

_{│<<<Laws of reflection│   │Reflection from plane surface>>>│}

---

Related Topics: Introduction to optics   Laws of reflection    Sign Convention  Reflection from plane surface   Spherical Mirror   Image formed in Concave mirror   Spherical Abberation  Refraction   Refractive Index    Refraction from plane surface   Lenses  Refraction from Curved surface  Lens makers Equation  Dispersion Of Light  Prism Formula