A power converter can be interpreted as two different things.
An adapter (shown) converts a US plug to a French plug and works with the French voltage. Pretty much everything made in this century with a power brick/cube of some sort is capable of working with a range of voltages, which is detailed on the fine print on the brick. What doesn't always work is hair dryers and other appliances which don't have a brick. My hairdryer has a manual switch to change between voltages.
A transformer (heavy and bulky) will change the French voltage to US voltage.
