O-LevelPhysicsLight5054/21 · May/June 2023 · Q66 Marks

The virtual reality headset in Fig. 6.1 contains a display and a lens, as shown in Fig. 6.2. [Figure 6.1] [Figure 6.2 (not to scale)] The display is the object for the lens. The lens acts as a magnifying glass and forms a virtual image of the display.

(a)(i)Describe where the display must be positioned relative to the focal length of the lens for the lens to act as a magnifying glass for the image on the display.[1]
(a)(ii)Explain how a virtual image is formed.[1]
(b)(i)On Fig. 6.3, draw a ray diagram to show the formation of the virtual image I.[3]
(b)(ii)Determine the focal length of the lens.[1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (May/June 2023). The mark or mark type is shown in brackets.

[B1] object within focal length / same distance from lens as the focal length
[B1] from divergent / parallel rays or rays followed back (behind lens meet at point on image or rays do not meet on a screen / do not converge or rays appear to come from image
[B1] ray through optical centre from top of object
[B1] ray parallel to axis from top of object to lens and line from junction with lens to top of image
[B1] both rays extended back to image and ray parallel to axis correctly refracted through lens to appear to come from top of image
[B1] 4(.0 cm)

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