Fig. 1 shows a ray diagram made by a museum technician who is designing a magnifying viewer for insect wings. A small object is placed between a convex lens...

Fig. 1 shows a ray diagram made by a museum technician who is designing a magnifying viewer for insect wings. A small object is placed between a convex lens and its principal focus. The dashed rays show the image seen by the visitor. The image is not formed on a screen, but appears behind the object when the visitor looks through the lens. The technician wants visitors to see a large, upright image without using electrical equipment. The diagram includes the principal axis, the lens and the focal points.

(a) What type of image is produced by the viewer? [1]
(b) Describe two features of the image compared with the insect wing. [2]
(c) Explain why a visitor cannot project this image onto a white card. [1]

The diagram shows an underwater diver wearing a mask with a flat glass window. Without the mask, the diver's eyes cannot focus clearly on a fish because water is in contact with the cornea. The air space inside the mask restores a boundary between air and the cornea. In Fig. 1, a light ray from the fish travels through water, glass and air before entering the eye. The diver notices that nearby objects can appear closer than they really are.

(a) Name the process occurring when the ray passes from water into glass. [1]
(b) Explain why the diver needs an air space in front of the eye. [2]
(c) Describe what happens to the velocity of light when it enters glass from water. [1]
(d) Give one reason the mask window is made from transparent material. [1]