Given: A red laser pointer emits light with a wavelength of 690. n m . The frequ

Question

Given: A red laser pointer emits light with a wavelength of 690. nm.

The frequencey of light is 4.34x10^14 s^-1

Part A: What is the energy of one of these photons?

Part B: The laser pointer emits light because electrons in the material are excited (by a battery) from their ground state to an upper excited state. When the electrons return to the ground state, they lose the excess energy in the form of 690. nm photons. What is the energy gap between the ground state and excited state in the laser material?

Both answers in "J" please

Explanation / Answer

a) energy = hf = 6.626 *10^-34 * 4.34 *10^14 = 2.876 *10^-19 J

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b) By conservation of energy, the energy gap between excited state and ground state must equal the photon energy. The energy of a photon

hence

E = 2.876 *10^-19 J

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