Refraction At A Curved Surface

Question 1

Define: converging and diverging spherical refractive surfaces

Answer 1

Converging refractive surface: will bring rays of light together to form a real image.

Diverging refractive surface: will bend the rays further away from one another forming a virtual image.

Question 2

Define: vertex, centre of curvature and principal axis

Answer 2

Vertex: distance from the back surface of the correcting lens and the front surface of the cornea.

Centre of curvature: the centre of the lens which forms part of a sphere.

Principal axis: imaginary straight line which passes through the centre of curvature.

Question 3

Power of refracting surface

Answer 3

Power of refracting surface is the degree in which a lens converges or diverges light. Measured in dioptres.

Question 4

Formula to work out power of a lens

Answer 4

F = (n’ - n) / r