New to Powershell: find url

Hello, I am new to powershell. I needed a help on a script. Basically, I have internet Explorer open to a certain url. I need my script to retrieve that url. 

$shell = New-Object -ComObject Shell.Application

 $result = $shell.Windows()

 $result.locationurl |

I know its something like this. but im lost. How can i find the url, as long as my internet explorer is open.