How many milliamperes are in one ampere?

One ampere is equal to 1000 milliamperes. This measurement comes from the definition of the metric prefix "milli," which denotes a factor of one-thousandth. Therefore, when converting amperes to milliamperes, you multiply the number of amperes by 1000.

For instance, if you have one ampere, when you apply the conversion factor, it results in 1 A × 1000 mA/A = 1000 mA. This understanding is important in various contexts, especially in healthcare and radiology, where precise measurements of current can significantly impact the functioning of medical equipment and patient safety.

In the context of the other options, they represent incorrect conversions. For example, 100 mA and 500 mA are both much less than one ampere, while 2000 mA exceeds the correct number. Thus, acknowledging that one ampere is exactly equivalent to 1000 milliamperes clarifies the relationship between these units of electric current.