The energy emitted or absorbed (∆E) is an integral multiple of 

An electron jumps from a lower-energy level to a higher-energy level, by absorbing energy, but when it jumps from a higher- to lower-energy level, the energy is emitted in the form of electromagnetic radiation. The energy emitted or absorbed (∆E) is an integral multiple of ‘hν. 

h-Plank’s constat 

ν-frequency