Question

What do you meant by quantisation of energy of electron

Answer 1

Quantisation means that a quantity can't change gradually and continuously but abruptly and discontinuously to have certain definite and discrete values . Bohr postulated that electron can revolve only In fixed orbits in which they canrevolve without gaining or loosing energy. This means energy of electron have certain definite values. So energy of an electron is quantised

Answer 2

'quanta' is the smallest packet of energy.
ie, e=1.6×10^-19
quantisation of charge means q(charge) always exist as integral multiples of whole numbers.
q=ne, where n=0,1,2,3,......