Refraction at curved surfaces

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
Principal axis

Answer 2

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

Centre of curvature - is the centre of the lens which forms part of a sphere

Principle axis - imaginary straight line which passes through the centre of curvature

Question 3

Define:

Power of a refracting surface

Answer 3

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

Question 4

Formula to work out power of a lens

Answer 4

F = (n’ - n) / r