Explain how a converging lens forms a real image of a distant object.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
A converging lens is used in a camera to focus light from a distant scene onto a sensor.
Model answer (4 marks)
Parallel rays from a distant object strike the converging lens.
The lens refracts the rays, bending them towards the optical axis.
The refracted rays converge at the focal point (principal focus) of the lens.
Because the rays actually meet at this point, the image formed is real.
The lens refracts the rays, bending them towards the optical axis.
The refracted rays converge at the focal point (principal focus) of the lens.
Because the rays actually meet at this point, the image formed is real.
Examiner tips
- Use the word ‘parallel’ to show the object is far away. Mention ‘refract’ and ‘bend’ to describe the lens action. State that the rays meet at the focal point. Explain that a real image is produced when rays physically converge.
Common mistakes
- Confusing a real image with a virtual image. Forgetting to mention that the rays meet at the focal point. Using ‘focus’ instead of ‘focal point’ or ‘principal focus’.
Mark scheme (4 marks)
- Parallel rays of light from a distant object strike the converging lens
- The converging lens refracts / bends the rays
- The rays are brought together / converge at the focal point (principal focus)
- The image formed is real because the rays actually meet / pass through the image point