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Voltage across capacitor

  • Thread starter pmontone
  • Start date
  • #1
2
0

Homework Statement


Voltage across 0.2-F cap is given by

v(t)=4(1-Є^(-10t)) for t>0


determine expression for the current i(t)

Homework Equations



i(t)=c (dv(t))/dt

The Attempt at a Solution



I'm really not sure were to begin with this problem what is the Є symbol and how do you take the derivative of it?
 

Answers and Replies

  • #2
Mapes
Science Advisor
Homework Helper
Gold Member
2,593
17
pmontone, you're in luck. That's not a Є symbol, but rather the constant e (= 2.718), the basis for the exponential function.
 
  • #3
532
2

Homework Statement


Voltage across 0.2-F cap is given by

v(t)=4(1-Є^(-10t)) for t>0


determine expression for the current i(t)

Homework Equations



i(t)=c (dv(t))/dt

The Attempt at a Solution



I'm really not sure were to begin with this problem what is the Є symbol and how do you take the derivative of it?
First, look at your given equation v(t) and try to understand its meaning. What happens to v(t) as t increases? Is this equation representative of a "charging" or "discharging" capacitor? Now, based on this answer, how do you expect the current across the capacitor to behave over time? Use your equation and then analyze the result for physical accuracy. Remember that a fully-charged capacitor acts as an open circuit (no current).
 

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