Differential Equations - Elementary Application

Electric Circuits

Please solve completely. Thank you.

An RL circuit has the following values: R=550 ohms, L=4 henrys and Esub0=110 volts. If i(0)= 0 in the circuit, when does the current reach 90% of its limiting value?

Using the formula: E = Ri + Ldi/dt

I integrate it and got:
Et = Rit + Li + E0

When i(0)=0, substituting to the equation..
E=0

The equation will be then:
E0= -Rit - Li

Subsituting values:
R= 550 , L=4 , E0=110
I got
110= -550it - 4i
110= -i (550t-4)
i= -110 / ( 550t -4)

What should I do with this information then?

The problem states that the other i is 90% of the limiting value. How can I solve for the limiting value?

3. A resistance of 100 kΩ is connected in series with a 100 μF capacitor. If the combination is suddenly connected across a 125 V dc source. Determine the current one second after the switch is closed.

Add new comment

Deafult Input

  • Allowed HTML tags: <img> <em> <strong> <cite> <code> <ul> <ol> <li> <dl> <dt> <dd> <sub> <sup> <blockquote> <ins> <del> <div>
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
  • Mathematics inside the configured delimiters is rendered by MathJax. The default math delimiters are $$...$$ and \[...\] for displayed mathematics, and $...$ and \(...\) for in-line mathematics.

Plain text

  • No HTML tags allowed.
  • Lines and paragraphs break automatically.