Final answer:
The exposure time required when 60 mAs is needed and the mA setting is at 400 mA would be 0.15 seconds, calculated by dividing the mAs by the mA.
Step-by-step explanation:
To calculate the exposure time when the milliampere-seconds (mAs) is given, and the milliamperes (mA) is set, you use the formula:
Exposure Time (s) = mAs / mA
In this particular situation, you have been given that 60 mAs is needed and the mA is set at 400 mA. By plugging in the values:
Exposure Time (s) = 60 mAs / 400 mA
Exposure Time (s) = 0.15 seconds
This means that the exposure time needed is 0.15 seconds.