The power of the shower

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In winter, heating bills are higher than during the rest of the year. Still, it can be cold and taking a long warm shower can be tempting. A problem with this is that the longer you shower, the more money it costs you. You might even say that you’re being charged per droplet of water coming from the shower head and I wouldn’t argue with that. However, I do think it’s funny that you’d mention charged droplets because that is just the thing I wanted to talk about for a moment.

Being charged per droplet when showering is like what happened in Millikan’s oil drop experiment.

In 1909, Robert Millikan and Harvey Fletcher found a way to measure the charge of a single electron. Their experiment used a fine mist of tiny oil droplets, which floated down under the force of gravity. On their way down, the droplets passed through an X-ray beam energetic enough to strip off some electrons from the droplet’s molecules here and there. As a result, some of the originally neutral droplets now obtained a net charge. Switching on an electric field then adds another force working on the droplets but only on the charged droplets. Charged droplets, feeling the pull of gravity and of the electric field, now float at a faster speed than neutral droplets which only feel the force of gravity. When looking at the speeds of the falling droplets, one can see that they only move at a few discrete speeds with no intermediate speeds. This indicates that the droplets do not contain just any random amount of charge but that they only contain discrete multiples of a fundamental unit of charge: that of a single electron.

Still, while interesting, the above does not help you with your bills. If therefore you are more interested in the fundamental unit of money (the penny), then I also have a way of saving more money by using less hot water. Rest assured that I am not talking about taking shorter showers though. No, instead I will suggest a water-saving shower head. They are designed to save water by having a reduced flow throughput. Because less water flows through the shower head per unit time, less hot water needs to be used for the same duration of showering. The shower does not reduce to a trickle though. A special design makes it feel as if you still receive the same amount of water while actually using up to 50% less. I’ve seen an explanation once saying that the droplets coming from such a shower head have a little air bubble inside so that the same size drop contains less water. In this way you can cut back on your spending without shortening your shower time. Win-win!