Add columns to existing libraries in SharePoint 2010 using Powershell

I need to add five new columns to existing SharePoint 2010 libraries using powershell.

I am using below script:

$ver = $host | select version 
if($Ver.version.major -gt 1) {$Host.Runspace.ThreadOptions = "ReuseThread"} 
if(!(Get-PSSnapin Microsoft.SharePoint.PowerShell -ea 0)) 
{ 
Write-Progress -Activity "Loading Modules" -Status "Loading Microsoft.SharePoint.PowerShell" 
Add-PSSnapin Microsoft.SharePoint.PowerShell 
} 


$SourceWebURL = "http://sitecollection/sites/site" 
$SourceLibraryTitle = "libraryName" 


$ssite = Get-SPSite $SourceWebURL
$sweb = $ssite.OpenWeb("subsite")



#$sWeb = Get-SPWeb $SourceWebURL 
$sList = $sWeb.Lists | ? {$_.Title -eq $SourceLibraryTitle} 


$spFieldType = [Microsoft.SharePoint.SPFieldType]::Text
$sList.Fields.Add("YourColumn",$spFieldType,$false)
$sList.Update()

Column is getting created but it is not showing in the library