Suppose you were stranded on a desert island with only a convex lens and a mirror. Describe how you could use each of these tools to signal for help.
To use the convex lens to signal for help, you could start by finding a spot on the beach where the sun is shining brightly. Hold the lens up towards the sun and focus the sunlight into a concentrated beam. Use this beam to target any passing ships or aircraft by moving the lens around and reflecting the bright light towards them. The concentrated light should catch their attention and signal that someone is in need of help on the island.
As for the mirror, you can use it in a similar way by reflecting sunlight towards potential rescuers. Hold the mirror up and angle it in such a way that the sunlight reflects off the mirror in a bright and noticeable manner. By repeatedly flashing the mirror towards passing ships or aircraft, you can create a series of bright flashes that can be seen from a distance. This flashing signal is a universal distress signal that can alert others to your presence on the island and the need for assistance.