The 'North pole' of any magnet is the one that would be attracted to the Earth's North magnetic pole. In that sense, they are just labels that identify the opposite magnetic force produced at each end of the magnet. The Earth'smagnetic field also has poles, North and South. more at study.com
<span>In blues musicians also often refer to chord progressions using Roman numerals, as this facilitates transposing a song to a new key. For example, rock and blues musicians often think of the 12 bar blues as consisting of I, IV and V chords.
Thus a simple version of the 12 bar blues might be expressed as I/I/I/I IV/IV/I/I V/IV/I/I. By thinking of this blues progression in Roman numerals, a backup band or rhythm section could be instructed by a band leader to do the chord progression in any key.
For example if the band leader asked the band to play this chord progression in the key of C Major, the chords would be C/C/C/C F/F/C/C G/F/C/C.</span>
On your list you can easily identify by knowing which is not a chemical change.
A physical change is a change not involving the material composition of the water. e.g. (melting, solidifying, evaporation). As long as the change does not change the molecular composition of the water which is H20 it is physical change.
Frequency = how many waves you get per sec
Period = how long each wave takes
Period = 1/frequency
