## Giving Credit Where Credit Is Due: Travel Electric Plug Converter

One of the handiest inventions in our modern world are the little plug attachments that allow machines built for the 110v electricity found in the United States to be used in foreign countries where 220-240v electricity is used, without damage. Today, I would like to talk about how and why these marvelous little electronics work, and their importance.

It is obvious to see why a traveling person (like myself) who carries around electronic laptops, cell phones, shavers, and so on would want to have a tool that allowed them to use electricity without damage to their technology all over the world. Of course, it would be convenient if everyone used the same voltage in their electricity, but we cannot expect everyone to act according to our whims and preferences. The fact that such electronics as plug converters can be easily and reliably made makes such uniformity unnecessary.

Let us now enter (briefly) the realms of engineering and mathematics to explain how it is that a plug converter works. There are really two tasks that a plug converter serves. The most trivial one is to connect the male plug of one design to the female socket of another configuration. That is easily enough done, without any electronics being involved. All one needs is good enough plastics and metals and the ability to form them properly to be able to accomplish that task.

More challenging is the second task of a plug converter, to get a machine that works with one voltage to work with another. Let us simplify the question and use Ohm’s law to illustrate this problem. According to Ohm’s law, voltage equals current divided by resistance. V = I*R. If you double the voltage, to keep the same current (which is what causes damage to electronics and human beings), you must double the resistance to balance the equation. And that is what the travel converters do. They double the resistance of the electronics to cause the increased voltage to end up with the same amount of current that is used back home so that a computer or shaver or cell phone can be used safely. And that is a remarkable achievement.

I am unaware of whether travel converters exist the other way, though there is no reason why they could not. The first problem, that of plug configuration, is just as trivial one way as the other. The second problem is more difficult. It is easy to multiply resistance as one increases voltage–that is simply a matter of adding or changing resistors. To reverse the process, though, would require electronics like an op-amp. One would have to “double” the voltage through the op-amp to counteract for the greater resistance in the machinery to balance the equation the other way, unless one wanted (or was willing) to work with a lower current and thus lower performance. And it should be as feasible to make an op-amp as it would be to make a resistor, albeit somewhat more complicated.

So, we should raise our glasses in the air and perform a salute for the humble and often neglected travel converter. For the skill of its design and creation allow it to perform too functions, both the physical fitting of the plug into the socket, as well as the more complicated but still very feasible task of tweaking the voltage and/or resistance so that the current remains constant and the electronic able to be used without damage from too much (or too little) electric charge. We can go where we want and use our electronics because other people have thought of and solved these problems relating to electricity–and we can be grateful for that.