{{tag>current charge chapter1_4}}
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#@TaskTitle_HTML@##@Lvl_HTML@#~~#@ee1_taskctr#~~ Determining the Current from Charge per Time                   #@TaskText_HTML@#   

Two objects experience a charge increase per time. In the <imgref l9hubowt6x00b2h5_1> one can see these increases in the charge per time. 

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<imgcaption l9hubowt6x00b2h5_1| Time course of the charge>
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1. Determine the currents $I_1$ and $I_2$ for the two objects from the $Q$-$t$-diagram <imgref l9hubowt6x00b2h5_1> and plot the currents into a new diagram.

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  * Have a look how much increase $\Delta Q$ per time duration $\Delta t$ is there for each object.
  * For this choose a distinct time period, e.g. between $0~\rm s$ and $20~\rm s$.
  * The current is then given as the change in charge per time: $I= {{\Delta Q}\over{\Delta t}}$
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{{drawio>l9hubowt6x00b2h5_2.svg}}
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2. How can the current be determined, when the charge increase on an object changes non-linearly?

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A non-linear charge increase leads to a non-constant current. \\
For a non-constant current, one has to use the time derivative of the charge $Q$ to get the current $I$. \\
So, the formula $I= {{{\rm d} Q}\over{{\rm d} t}}$ has to be used instead of $I= {{\Delta Q}\over{\Delta t}}$.
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