How can I call a file from the same folder that I am in (in script)

How about this:

& $pwd\scriptb.ps1

it is possible using $MyInvocation as follows:

$executingScriptDirectory = Split-Path -Path $MyInvocation.MyCommand.Definition -Parent
$scriptPath = Join-Path $executingScriptDirectory "scriptb.ps1"
Invoke-Expression ".\$scriptPath" 

i use the powershell variable which has an easy name to remember what is it for.

$PSScriptRoot\scriptb.ps1