# Thread: find the charge q(t) flowing thru a device if the current is:

1. ## find the charge q(t) flowing thru a device if the current is:

$\displaystyle A=$Amperage $\displaystyle C=$Coulombs

$\displaystyle i(t)= 3A$, $\displaystyle q(0) = 1C$

The Ans is $\displaystyle 3t+1$

this is very new subject to me but I assume we want to use

$\displaystyle Q \triangleq \int_{t_0}^t i \ dt$

2. Originally Posted by bigwave
$\displaystyle A=$Amperage $\displaystyle C=$Coulombs

$\displaystyle i(t)= 3A$, $\displaystyle q(0) = 1C$

The Ans is $\displaystyle 3t+1$

this is very new subject to me but I assume we want to use

$\displaystyle Q \triangleq \int_{t_0}^t i \ dt$
Yes,

$\displaystyle \displaystyle\ i=\frac{dQ}{dt}\Rightarrow\ Q=\int{i}dt$

$\displaystyle \displaystyle\int{i}dt=Q=it+q(0)$

where $\displaystyle q(0)$ is the initial charge.

3. ## then we just plug

so for

$\displaystyle \int{i}dt=Q=it+q(0)$

then we just plug in $\displaystyle 3$ into $\displaystyle it$ and $\displaystyle 1C$ into the q(0)

to get the $\displaystyle 3t + 1C$

4. Yes, that's all that's required Bigwave.
A constant current of 3 Amps will cause the passing charge through the device to ramp up linearly with time.

5. I'll be posting a lot more EE stuff if you are up for it.... brave new world for me...

6. Ok Bigwave!
I will keep an eye out for those.

,

,

,

,

# find charge q(t)

Click on a term to search for related topics.