Thin lenses

What the syllabus asks of you

• Describe the action of thin converging and thin diverging lenses on a parallel beam of light
• Define and use the terms focal length, principal axis and principal focus (focal point)
• Draw and use ray diagrams for the formation of 6 Draw and use ray diagrams for the formation of a real image by a converging lens a virtual image by a converging lens
• Describe the characteristics of an image using 7 Describe the use of a single lens as a the terms enlarged/same size/diminished, magnifying glass upright/inverted and real/virtual
• Know that a virtual image is formed when diverging rays are extrapolated backwards and does not form a visible projection on a screen 8 Describe the use of converging and diverging lenses to correct long-sightedness and short- sightedness