How many electron volts are in one kilo-electron volt?
What this question is asking us is to identify the unit prefix k. Unit prefixes are letters that you put in front of other normal units in order to show that they are very large or very small, with each prefix indicating a different amount that the base unit is changed by. One we may be familiar with involves meters. When measuring large distances, we may use kilometers, or km, with a single kilometer being equal to one times 10 to the power of three meters, which is equal to 1000 meters. The reason we use these unit prefixes is to keep the numbers small and manageable. You wouldn’t say to a friend that you were 30000 meters away. you would say you’re 30 kilometers away.
And this is especially relevant when we look at electron volts. One electron volt is a very small amount of energy. So typical measurements in electron volts usually have quite a few zeros after them, meaning that unit prefixes are common. And using our knowledge of unit prefixes, this k in front of the eV is kilo, or 10 to the power of three. In order to convert kilo-electron volts into regular electron volts, we have to multiply it by 10 to the power of three. So one times 10 to the power of three equals 1000. This means in one kilo-electron volt, there are 1000 regular electron volts.