The total energy of an electron in the first excited state of the hydrogen atom is about –3.4 eV.
(a) What is the kinetic energy of the electron in this state?
(b) What is the potential energy of the electron in this state?
(c) Which of the answers above would change if the choice of the zero of potential energy is changed?
The total energy of an electron in the first excited state of the hydrogen atom is about –3.4 eV.
(a) What is the kinetic energy of the electron in this state?
(b) What is the potential energy of the electron in this state?
(c) Which of the answers above would change if the choice of the zero of potential energy is changed?

Answer –

(a) Total energy of the electron is given by E = – 3.4 eV

We know that the kinetic energy of the electron is equal to the negative of the total energy. So,

K.E = – E

K.E = – (- 3.4 ) = + 3.4 eV

Therefore, Kinetic energy =  + 3.4 eV

(b) It is also known to us that the Potential energy (U) of the electron is equal to the negative of two times of the kinetic energy, so –

P.E = – 2 (K.E)

= – 2 x 3.4 = – 6.8 eV

Therefore, Potential energy = – 6.8 eV

(c) The potential energy of the system is dependent upon the value of reference point. When the reference point is modified/changed from zero, it will result in change in the potential energy. And as we know that the total energy is given by the sum of the potential energy and kinetic energy. Therefore, the total energy will also change with the change in reference point