Notes Physics

Energy Quantization


Bohr suggested that the electron in the atom exist in discrete energy known as quantization which can be removed from one level to the other. Energy in such bodies is emitted in separate or discrete

energy packet called energy quanta

                                  E =hf

                                  h = Planck’s constant.

                                  f = frequency


Electrons in atoms are arranged around their nuclei in position known as energy level or electron shell. It requires more energy to remove electrons from the first  energy level than to remove electrons from any of the other higher levels.  The energy of an electron is given by the relation .


  1. With the aid of a diagram, explain charge distribution
  2. Name two devices that can store charge.


New School physics pgs


1.   When an atom is in ground state, it is said to be (A) excited (B) stable (C) ionized

2.   In which of the following transitions is the largest quantum of energy liberated by an hydrogen atom, when the electron changes energy level? (A) n=2 to n=1 (B) n=2 to n=3 (C) n=3 to n=2

(D) n=1 to n=2

3.   Which of the following give rise to the line spectra obtained from atoms. (A) change of electron from a higher to lower energy level (B) potential energy of the electron inside an atom

      (C ) Excitement of an electron in the atom

4.   A 50KV is applied across an x-ray tube. Calculate the maximum velocity of the electrons produced. [Me= 9.11X10-31Kg, e= 1.6X10-19C] (A) 4.2X108m/s (B) 1.8X108m/s (C) 4.2X105m/s

(D) 1.8X105m/s

5.   The nucleon number and the proton number of a neutral atom are 238 and 92 respectively. What is the number of neutrons in the atom? (A) 146 (B) 330 (C) 73 (D) 52.


1.   An electron of charge 1.6X10-19C is accelerated in a vacuum from rest at zero volt towards a plate 40KV. Calculate the kinetic energy of the electron

2.   An electron jumps from one energy level to another in an atom radiating 9.0×10-19J.     If h = 6.6 x 10 -34Js and C = 3.0 x 108m/s, what is the wavelength, and the frequency of the radiation.

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