A ruby laser can deliver a 4.33-J pulse in approximately 50 nanoseconds.The wavelength of the light is 694 nm.At least how many atoms within the ruby rod had to be excited to allow this high-energy laser pulse? (h = 6.63 × 10−³⁴ J⋅s,c = 3.00 × 10⁸ m/s,1 eV = 1.6 × 10−¹⁹ J,and 1 nm = 10−⁹ m) A)3.5E+18 B)3.0E+17 C)1.5E+19 D)1.5E+21 E)1.1E+18

Question

Quizplus · Accepted Answer

The energy of a single photon is calculated using E = hc/λ. Substituting the given values, E = (6.63 × 10^-34 J⋅s)(3.00 × 10^8 m/s) / (694 × 10^-9 m) = 2.86 × 10^-19 J per photon. The number of photons (and thus the number of excited atoms) is the total energy divided by the energy per photon: 4.33 J / 2.86 × 10^-19 J/photon ≈ 1.5 × 10^19 atoms.

A Ruby Laser Can Deliver a 4