In Bohr's atomic model of hydrogen, let K, P and E are the kinetic energy, potential energy and total energy of the electron respectively. Choose the correct option when the electron undergoes transitions to a higher level :

Solution

Physics sir · 3 steps

Lock in K = -E and P = 2E; as E climbs towards zero, K has to fall.

1. Link the three. For an electron in a Bohr orbit, the electrostatic pull supplies the centripetal force. This gives K = ke²/2r and P = -ke²/r, so P = -2K and E = K + P = -K.

   Eₙ = -13.6/n² eV, Kₙ = +13.6/n² eV, Pₙ = -27.2/n² eV

   Quantity	n = 1	n = 2	Change on going up
   K	13.6 eV	3.4 eV	decreases
   P	-27.2 eV	-6.8 eV	increases (less negative)
   E	-13.6 eV	-3.4 eV	increases (less negative)

2. Why it happens. A higher level means a bigger orbit, where the electron moves more slowly, so K drops. P and E are negative and move closer to zero, so their values rise.
3. So. K decreases while P and E both increase, which is option (b).

The idea to keep. In any Bohr orbit, K = -E and P = 2E. Absorbing energy makes E less negative, so P rises with it and K falls. Compare signed values, not magnitudes.

Answer from the NTA final answer key. Solution by PrepWiser.