Simplify the following text for a Grade 6 native English-speaking person.
Original: The Planck constant was first described as the proportionality constant between the energy ( E ) of a photon and the frequency of its associated electromagnetic wave ( Î 1\/2 ) . This relation between the energy and frequency is called the Planck relation or the Planckâ `` Einstein equation :
Simplified: where E stands for energy , H is the Planck constant and F is the frequency .