Question

According to Bohr's model of the atom, atoms emit or absorb radiation only at certain wavelengths.Identify why is it so

• A. Because the protons and electrons are distributed evenly throughout the atom
• B. Because electrons can orbit the nucleus at any radius
• C. Because electrons orbit the nucleus only at certain discrete radii
• D. Because protons orbit the nucleus only at certain discrete radii
• E. Because photons can only have discrete wavelength

Answer 1

The correct option is C Because electrons orbit the nucleus only at certain discrete radii

Bohr's frequency condition is given by $hc/\lambda =E_2-E_1$

Above relation shows that wavelength $\lambda$ of radiation depends upon energy difference of two orbits, $\lambda$ is certain because energy difference is constant for two orbits it means $E_1$ and $E_2$ are also fixed i.e. electron is revolving in some fixed orbits of discrete radii.These orbits are called stationary orbits in which electron does not emit energy when revolving in these orbits.