in the creation of a VolumeGroup I define the physical extent to 2mb, so my logical extents will be that size (2mb) when I create a logical Volume?
Logical volumes take up an integer number of physical extents from the space allocated to volume group. The physical extents allocated to a logical volume are then called logical extents, but they are the same thing and thus have the same size. The difference between physical extents (in a volume group) and logical extents (in a logical volume) is simply of numbering: the logical extents in the logical volume are numbered sequentially from 0, but they are mapped into one or more segments (that is, ranges) of physical extents in the volume group.
$ sudo lvs -o full_name,size,seg_pe_ranges LV LSize PE Ranges Serverax/Home 9.50g /dev/mapper/Serverax:5302-7733 Serverax/Root 19.50g /dev/mapper/Serverax:310-5301 Serverax/Srv 5.50g /dev/mapper/Serverax:7734-9141 Serverax/Swap 1.21g /dev/mapper/Serverax:0-309