4. [1.5 points] To constantly travel around a circuit orbit, the circumference of the orbit must be an integer number of electron wavelengths. A) half-integer number; B) integer number; C) prime number; D) imaginary number; E) None of the above
5. [1.5 points] In the Bohr model, an atom radiates energy only when an electron makes a transition from an orbit of energy (Eu to a different orbit with lower energy E, emitting a photon of energy hf=En-En in the process. A) transition, emitting; B) transition, absorbing; C) power, emitting; D) power, absorbing; E) None of the above
6. [1.5 points] For a photon, the energy E, frequency f, and wavelength are related by the equations E=hf, E= hc/λ, and f=c/λ. Here h is Planck's constant and c is the speed of light in vacuum. Which of these equations also applies to electrons?
