Question

According to the Cartesian sign convention for refraction at a spherical surface, all distances are measured from:

Options

• The centre of curvature

• The focal point

• The pole

• The point of incidence of the ray

Answer 1

In the Cartesian sign convention, all distances are measured from the pole of the spherical refracting surface. Distances in the direction of incident light are positive, distances opposite to it are negative, and heights are measured with respect to the principal axis.