A converging lens can be used to form a real image of a distant object. Explain how a converging lens produces a real image, and describe one difference between a real image and a virtual image.

Eduqas GCSE Physics — 2.1 Light, lenses and the universe · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

A converging lens refracts light rays, bending them towards the optical axis. Rays that pass through the lens are brought together and converge at a point called the focal point. Where the refracted rays actually meet or cross, a real image is formed. A real image can be projected onto a screen, whereas a virtual image, which is formed where the rays appear to meet but do not actually cross, cannot be projected.

Examiner tips

  • Use the word ‘refract’ and ‘converge’ to show understanding of lens action.
  • State that a real image is where rays actually cross and can be projected.
  • Mention the key difference: virtual images cannot be projected onto a screen.
  • Keep the answer concise – 4 marks only.

Common mistakes

  • Confusing a virtual image with a real image – forgetting that real images are formed where rays cross.
  • Using the wrong terminology (e.g., ‘diverge’ instead of ‘converge’).
  • Failing to mention that a real image can be projected onto a screen.

Mark scheme (4 marks)

  1. A converging lens refracts (bends) light rays
  2. Rays passing through the lens are brought together (converge) at a point called the focal point / focus
  3. A real image is formed where the refracted rays actually meet / cross
  4. A real image can be projected onto a screen, whereas a virtual image cannot / a virtual image is formed where rays appear to meet (but do not actually cross)

Key terms in this question

converging lens · real image · virtual image

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