4. Which optical device(s) on the list below will always give a virtual image a real object regardless of how far the object is away from the device?

* 32. Use ray diagrams to locate the images of the following objects: (a) an object that is 10 cm from a convex lens of +15-cm focal length and (b) an object that is 10 cm from a concave lens of -15-cm focal length. (c) Calculate the image locations for parts (a) and (b) using the thin lens equation. Check for consistency.

1. A patient enters an eye doctor’s office and finds the doctor tells him that his near point is 10.0 cm. The doctor also finds the patient’s far point (with eyes relaxed) is 125 cm. Each eye lens can be assumed to be 2.00 cm from the retina. a) Between what limits (units: diopters) does the power of this patient’s lens (technically lens+cornea combination) vary? b) The doctor is going to prescribe glasses. Calculate the power of the eyeglass lens the patient should use for relaxed distance vision. Is the lens converging or diverging?

3. Two converging lenses above are placed 20.0 cm apart, both with focal lengths of 10.0 cm. A candle is 30 cm away from the first lens. By means of a neat ray tracing, locate the final image formed by the combination of the two lenses. b) Use mathematics to fully describe the image created by the lenses.

You are a marine biologist and want to pull a star fish out of a tank of water for testing. Looking from the top of the tank, where is the actual starfish compared to the image of the starfish that you see from the surface? Explain.