WPF- How to find the height/width of a WPF control added dynamically

//Dynamically cretaed TextBlock
TextBlock objTextBlock = new TextBlock();
objTextBlock.Loaded += new RoutedEventHandler(objTextBlock_Loaded);
//Access the dimensions using ActualHeight and ActualWidth in this event.

void objTextBlock_Loaded(object sender, RoutedEventArgs e)
{
TextBlock objTextBlock = sender as TextBlock;


MessageBox.Show(objTextBlock.ActualHeight.ToString());

MessageBox.Show(objTextBlock.ActualWidth.ToString());

}