(i) State Bohr postulate of hydrogen atom that gives the relationship for the frequency of emitted photon in a transition.

(ii) An electron jumps from fourth to first orbit in an atom. How many maximum number of spectral lines can be emitted by the atom? To which series these lines correspond?

OR

Use de-Broglie’s hypothesis to write the relation for the nth radius of Bohr orbit in terms of Bohr’s quantization condition of orbital angular momentum.

According to Bohr’s theory, When the electron jumps from one orbit to another it either absorbs or emits the energy in the form of quanta. The energy of each quanta is the difference between the energy level of the orbits.

Let’s consider the electron jumps from the energy level E₁ to energy level E₂ then,

hv=E₁-E₂

Where, h = Planck’s constant

v=Frequency

(ii) According to the Bohr’s theory the wavelength of the emitted photon is given by,

Where, λ=Wavelength

OR

De-Broglie’s hypothesis states that the stationary orbit contains the integral number of the wave of the revolving electron.

For nth orbit,

2πr=nλ

Using De- Broglie wavelength,

λ=h/mv

Using both equation we get,

2πr=n (h/mv)

2πr= nh/mv

This equation is the symbolical representation of Bohr’s second postulates.