Water refracts light much the way glass does; a water drop with perfect cur- vature can make a powerful lens. A simple magnifier can be made by twisting a piece of wire around a nail and dipping the loop briefly into some water. Students can observe the optical properties of the trapped drop of water.
Better imaging can be had if the drop is more perfect in shape – the asymmetry of the wire twisting distorts the image. Search for a piece of thin but stiff plastic – the firm, transparent packaging around new cell phone batteries works well. Cut a small piece of this plastic, perhaps 1×2 centimeters. Near one end, make a hole, the more perfect the better. The best hole-cutting tool is a paper hole punch, available in many schools. With care, fine scissors or a pen knife will suffice; remove all burrs.
• Materials: water, clear glass test tube
• Procedure: Fill the test tube with water. Put your thumb over the top of the test tube and turn it horizontal. Look through the water in the test tube to whatever needs magnifying.
• The light that passes through water refracts and gives rise to a magnifying effect. This magnifying effect is not terribly strong; maybe it magnifies things by a factor of two. This is better than nothing in terms of seeing small things.