# Calculating electric charge from graph (capacitor)

• krisu334

#### krisu334

Homework Statement
When charging a capacitor we obtained a graph of voltage in terms of time. From the graph, find the amount of electronic charge on the capacitor.
Relevant Equations
Initial voltage: 10 V
Capacity: 2*10^(-6) Fahr.
Resistance: 1*10^6 Ohm
Apparently, we need to integrate the functions from 0 to the time when it is fully charged. However, I integrated in terms of t so the soultion (according to a graph programme) should be around 236 Vs but I don’t see how this could help me.

Hello @krisu334 , ##\ ##!​
What is the expected relationship between ##V## and ##t##?

Homework Statement: When charging a capacitor we obtained a graph of voltage in terms of time. From the graph, find the amount of electronic charge on the capacitor.
Relevant Equations: Initial voltage: 10 V
Capacity: 2*10^(-6) Fahr.
Resistance: 1*10^6 Ohm

Apparently, we need to integrate the functions from 0 to the time when it is fully charged. However, I integrated in terms of t so the soultion (according to a graph programme) should be around 236 Vs but I don’t see how this could help me.
Hi @krisu334. In addition to @BvU ’s question:

Presumably V is the voltage across the capacitor. Are you charging or discharging? You say “Initial voltage: 10 V” which implies you are discharging. But you also say “from 0 to the time when it is fully charged” which implies charging.

Minor points, for information:
The unit of capacitance (not “capacity”) is the ‘farad’ (lower case), symbol ‘F’.
The unit of resistance is the ‘ohm’ (lower case), symbol ‘Ω’.

Well, what is the status?