Now, we will use the Notebook interface to repeat the calculations that we did with the interactive shell. We will add some text to document what we've done.
The empty white box in the middle of the worksheet is an input cell. Click in the input cell and type in the following text:
R = 250e3 # ohms C = 4e-6 # Farads tau = R * C tau
You can also insert an empty input cell by moving ...