Singing wine glasses and whistling bottles. Free

These are two experiments that are easy to do at home. The first is with a wine glass, it does not have to be fancy, but it must be a glass on a stem. Put some water in the glass and hold the glass firmly on the counter by the stem. Wet one of your fingers and run it around the rim of the glass. Eventually, the glass will sing. Change the amount of water in the glass, the pitch will change. A bottle is needed for the second experiment. It does not have to be a specific type of bottle or a certain height, it does not even need to be glass; however, it may be easiest with a bottle with a narrow neck and smaller opening like a soda bottle. With about half the bottle full of water, blow across the top of the opening of the bottle, trying not to blow directly into the bottle. You may have to adjust the angle at which you are blowing, but eventually the bottle will whistle. Now, change the amount of water in the bottle and the pitch will change. These singing household items use two different acoustic principles!