Answer the following question given this paragraph: Electromotive Force You can think of many different types of voltage sources. Batteries themselves come in many varieties. There are many types of mechanical/electrical generators, driven by many different energy sources, ranging from nuclear to wind. Solar cells create voltages directly from light, while thermoelectric devices create voltage from temperature differences. Q: Solar cells create voltages directly from light, while thermoelectric devices create voltage from differences in what? Choices: - oxygen - wire width - wattage - temperature A:
The answer to this question is:
temperature