Chapter 8

Types of lenses: 

• Convex (converging) lens

  • • Brings together rays of light passing through

• Concave (diverging) lens

  • • Spreads out rays passing through

Real vs Virtual image

• Real images have light rays which meet at image position

• Virtual images do not

Glossary of Terms

• Principal axis

  • Line passing through the optical centre of the lens and is perpendicular to the plane of the lens

• Optical centre

  • The literal centre of the lens. Rays passing through are not refracted, and do not deviate

• Principal focus (Focal point)

  • Point on the principal axis where an incident ray parallel to principal axis converges

• Focal length

  • Distance between focal point and optical centre

• Focal plane

  • Vertical plane which passes through focal point and is parallel to principal axis

Key principal rays:

• Ray parallel to principal axis

• Ray passing through optical centre

• Ray through focal point

Case studies: