1. The speed of light in a certain substance is 88% of its value in water. What is the index of refraction of that substance?
2. In a slide or movie projector, the film acts as the object whose image is projected on to the screen. A 105 mm focal length lens is to project an image on a screen 6.5 m away.
A. Decide how far from the lens the slide must be
B. Of the slide is 36 mm wide, how wide will the picture be on the screen?