411 REFERENCE · Wikibooks
OCR Advanced GCE in Chemistry/Colour/e=hf
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
e= energy
h= planck's constant (big number that doesn't change)
f= frequency of light
'Energy' basically means the amount of energy contained in each 'packet' of energy that arrives in light.