Calculations: Energy, Frequency, and Wavelength
1. What are the frequency and energy of blue light that has a wavelength of 400.00 nm?
Ans:  = 7.50 x 1014 Hz
E = 4.97 x 10-19 J
2. What are the wavelength and energy of light that has a frequency of 1.50 x 1015 Hz?
Ans:  = 2.0 x 10-7 m
E = 9.95 x 10-19 J
3. Calculate the wavelength of a photon of radiation whose frequency is 7.5 x 1012 Hz.
Ans:  = 4.0 x 10-5 m
4. A photon of radiation has a frequency of 3.33 x 1013 Hz. Calculate the energy in one mole of these
photons.
Ans: E = 1.33 x 104 J
5. Co-60 is used as a source of gamma rays in the treatment of certain cancers. If the wavelength of one
photon of this radiation is 1 x 10-8 Ao (Angstrom (Ao) = 10-8 cm), determine it’s energy.
Ans: E = 1.99 x 10-7 J
6. Heating sodium releases light with many different wavelengths. One of these has a wavelength of 589
nm. Calculate the energy associated with one photon of this light. Ans: E = 3.38 x 10-19 J
7. Calculate the number of photons having a wavelength of 10.0 m required to produce 1.0 kJ of energy.
Ans: 5.0 x 1022 photons
8. Calculate the energy released by a photon of radiation having a wavelength of 3.12 x 10-7 m.
Ans; E = 6.37 x 10-19 J
9. Calculate the energy for the 2nd energy level (n = 2) of Bohr’s hydrogen atom.
(Rydberg constant RH = 2.18 x 10-18 J).
Ans: E = 5.45 x 10-19 J
10. Calculate the energy of the 6th energy level (n = 6) of Bohr’s hydrogen atom.
Ans: E = 6.1 x 10-20 J
11. An electron in the Lyman series of a hydrogen atom transitions from n = 2. Calculate the frequency of
the photon released from this transition.
Ans:  = 2.47 x 1015 Hz
12. Calculate the wavelength in nm of a photon of light emitted in the Balmer series by a hydrogen atom
when n = 3.
Ans:  = 656 nm
13. Calculate the wavelength in nm of a photon of light emitted during a transition from n = 5 to n = 2.
Ans:  = 434 nm
14. Calculate the energy released by a photon of light in the Brackett series as it transitions from
n = 12.
Ans: 1.21 x 10-19J
15. Calculate the total energy in 12 dozen photons of UV radiation (ν = 1016 Hz).
Ans: E = 9.55 x 10-16 J
Equations: En = -RH(1/n2) where RH = 2.18 x 10-18 J
E = Ef – Ei = RH(1/ni2 – 1/nf2) and
E = h = hc/ = RH(1/ni2 – 1/nf2) to calculate frequency or wavelength