# Units question

1. ### ehrenfest

If a coulumb is defined as the amount of charge carried by a current of one Ampere in a second, why is its units Amperes seconds and not Amperes per seconds?

Last edited: Aug 11, 2007
2. ### mjsd

858
$$I=\frac{dQ}{dt}$$ by definition and so $$Q = \int I\;dt$$ which has a unit of (amperes x seconds)
seems obvious to me, do I understand your question correctly?

3. ### ehrenfest

Yes, I see how it works mathematically. But I just thought "the amount of charge carried by a current of one Ampere in a second" was similar to the amount of charge carried by a current of one Ampere per second" so it would have units of Amperes/S

4. ### mgb_phys

8,809
No because a coulomb is a total amount of charge not a rate, so after 2 seconds you have 2 coulombs.

5. ### mjsd

858
yeah, another example Energy = Power x time
and Energy is not a rate, while Power is. so amount of charge is like "energy" in this analogy