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A 100 W sodium lamp radiates energy uniformly in all directions. The wavelength of the sodium light is 589 nm . What is the energy per photon in ( eV ) associated with the sodium light? [ h = 6 .63 × 10 -34 J s ]

Options

  1. A2 .11
  2. B1.22
  3. C0.5
  4. D3.21

Correct answer

A. 2 .11

Step-by-step solution

Given, power of the lamp, P = 100 W The wavelength of the sodium light, λ = 5 8 9 nm = 589  ×  10 − 9  m Planck constant h  = 6 .63 × 10 -34  J s The energy of each photon E = hc λ = 6 . 6 3 × 1 0 - 3 4 × 3 × 1 0 8 5 8 9 × 1 0 - 9 ∵   c = 3 × 1 0 8  m s - 1 = 3 . 3 8 × 1 0 - 1 9  J = 3 . 3 8 × 1 0 - 1 9 1 . 6 × 1 0 - 1 9 eV = 2 .11 eV

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