20.1 A hydrogen atoms is in its ground state (n = 1). Using Bohr’s theory, calculate (a) the radius of the orbit, (b) the linear momentum of the electron, (c) the angular momentum of the electron (d) the kinetic energy (e) the potential energy, and (f)the total energy. [Ans: (a) 0.529 ï½˜ 10⁻¹⁰ m (b) 1.99 ï½˜ 10⁻²⁴ kg m s⁻¹ (c) 1.05 ｘ 10⁻³⁴ kg m² s⁻¹ (d ) 13.6 eV (e) - 27.2 eV (0 -13.6 eV)





20.8 The wavelength of K-x-ray from copper is 1.377 ｘ 10⁻¹⁰ m. What is the energy difference between the two levels from which this transition results? (Ans: 9.03 keV)



20.9 A tungsten target is struck by electrons that have been accelerated from rest through 40KV potential difference. Find the shortest wavelength of the bremsstrahlung radiation emitted? (Ans: 0.31 ｘ 10⁻¹⁰ m)



20.10 The orbital electron of a hydrogen atom moves with a speed of 5.456 ｘ10⁵ m s⁻¹ 

(a) find the value of the quantum number 'n' associated with this electron,

(b) calculate the radius of this orbit, and (c) the energy of the electron in this orbit? 

(Ans: n = 4. r₄ = 0.846 nm: E₄ = -0.85 eV)

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