Method 1 - Solving the DE

The formula is: MATH

After substituting:MATH

Solving:

MATH

I.F. = MATH

MATH

When $t=0$, $i=0$, so MATH

This gives us:MATH

The transient current is:MATH A

The steady state current is:$\qquad i=0.1$ A

Method 2: Using the Formula

NOTE: We can use this formula here only because the voltage is constant. This formula will not work with a variable voltage source.

We have:

RL7

So

MATH

5_RLex1__13.png

In this example, the TC is

MATH

So we see that the current has reached steady state by t = 0.2 × 5 = 0.1 s


Method 3: Using Scientific Notebook's Solve ODE

If you have Scientific Notebook, proceed as follows:

This DE has an initial condition i(0) = 0. We set up a matrix with 1 column, 2 rows.

For the answer: ComputeSolve ODE...Exact