Power chords Fifth chords are called power chords usually played on electric guitar with three or four notes, so A5 & G5 are power chords- A5- 002200 or 000775 G5-000553(it means first ,second,third strings are played open fourth string on 5th fret, Fifth string on 5th fret and Sixth string on 3rd fret)
G5 is played: e|------ B|------ G|------ D|--5--- A|--5--- E|--3--- A5 is played: e|------ B|------ G|------ D|--7--- A|--7--- E|--5--- It is basically the playing the Bar chord but only just the lower 3 strings of the chord. Mostly played this way for 1)convenience or 2) to give the chord a heavy sound by not playing the higher notes of the chord.
Try this webpage to find out how different chords are positioned and played along different frets on the guitar. https://www.all-guitar-chords.com/ Cheers! -Sameer