Work through these eight questions in order. They cover all four lessons in light and optics.
The timed practice session builder can turn the set into a timed run.
Questions
Question 1 (2 marks). State what happens to a ray parallel to the axis when it passes through a convex lens.
Answer
The ray bends and passes through the focal point F on the other side of the lens.
Question 2 (1 mark). State what happens to a ray that passes through the optical centre of a thin lens.
Answer
It carries straight on without bending.
Question 3 (3 marks). An object is 35 cm from a convex lens with focal length 10 cm. Describe the image.
Answer
2F = 20 cm and 35 cm is beyond 2F. The image is real, inverted and diminished, and forms between F and 2F.
Question 4 (2 marks). A student catches a sharp image on a screen. State whether the image is real or virtual, with a reason.
Answer
Real, because a real image forms where light rays actually meet, so it can be caught on a screen.
Question 5 (3 marks). Explain why a magnifying glass gives an upright image.
Answer
The object is inside the focal length. The rays leaving the lens spread out, so they only appear to come from a point behind the object. The eye sees a virtual, upright and magnified image.
Question 6 (3 marks). A convex lens has f = 12 cm. An object is placed 18 cm away. State the image position relative to 2F and describe the image.
Answer
2F = 24 cm, so the object sits between F and 2F. The image forms beyond 2F, and is real, inverted and magnified.
Question 7 (4 marks). Compare a camera and a slide projector in terms of the object position and the image.
Answer
A camera has the object beyond 2F, whereas a projector has the slide between F and 2F. The camera forms a real, inverted and diminished image, but the projector forms a real, inverted and magnified image.
Question 8 (4 marks). Label the parts of the eye that do these jobs: (a) lets light in, (b) bends light to focus, (c) receives the image. Name the matching camera part for each.
Answer
(a) Pupil, matching the aperture. (b) Eye lens, matching the convex lens. (c) Retina, matching the sensor or film.
If you got these wrong
- Questions 1 and 2: revisit drawing basic ray diagrams.
- Questions 3 to 6: revisit explaining image formation.
- Question 7: revisit comparing lens applications.
- Question 8: revisit interpreting optical-device diagrams.
Log each slip in the mistake log and paper-error review. To practise with a teacher, see online one-to-one Science tuition.