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Concepts Of Physics MCQ Edition [Volume 2]
Exam
Concepts Of Physics MCQ Edition [Volume 2]
Subject
Physics
Chapter
Photoelectric Effect and Wave–Particle Duality

Concepts Of Physics MCQ Edition [Volume 2] · Physics · Photoelectric Effect and Wave–Particle Duality

Determine the net energy absorbed by an atom during a process in...

Determine the net energy absorbed by an atom during a process in which it absorbs a photon of wavelength 500 nm500 \text{ nm} and subsequently emits another photon of wavelength 700 nm700 \text{ nm}.

Options

  1. A6.8×10−19 J6.8 \times 10^{-19} \text{ J}
  2. B4.0×10−19 J4.0 \times 10^{-19} \text{ J}
  3. C1.1×10−19 J1.1 \times 10^{-19} \text{ J}
  4. D2.8×10−19 J2.8 \times 10^{-19} \text{ J}

Correct answer

C. 1.1×10−19 J1.1 \times 10^{-19} \text{ J}

Step-by-step solution

The net energy absorbed by the atom is the difference between the energy of the absorbed photon and the energy of the emitted photon.

ΔE=Eabsorbed−Eemitted\Delta E = E_{\text{absorbed}} - E_{\text{emitted}}

ΔE=hcλabsorbed−hcλemitted\Delta E = \dfrac{hc}{\lambda_{\text{absorbed}}} - \dfrac{hc}{\lambda_{\text{emitted}}}

Substituting the given values, λabsorbed=500 nmand\lambda_{\text{absorbed}} = 500 \text{ nm} and\lambda_{\text{emitted}} = 700 \text{ nm}:<br><br>:<br><br>\Delta E = hc \left( \dfrac{1}{500 \times 10^{-9}} - \dfrac{1}{700 \times 10^{-9}} \right)<br><br>Usinghc = 6.63 \times 10^{-34} \times 3 \times 10^8 = 19.89 \times 10^{-26} \text{ J m}:<br><br>:<br><br>\Delta E = 19.89 \times 10^{-26} \times 10^9 \left( \dfrac{1}{500} - \dfrac{1}{700} \right)<br><br><br><br>\Delta E = 19.89 \times 10^{-17} \left( \dfrac{7 - 5}{3500} \right)<br><br>\Delta E = 19.89 \times 10^{-17} \times 23500<br><br>\dfrac{2}{3500}<br><br>\Delta E = 39.78×10−173500≈\dfrac{39.78 \times 10^{-17}}{3500} \approx1.136 \times 10^{-19} \text{ J}<br><br>Roundingtotwosignificantfigures,thenetenergyabsorbedis<br><br>Rounding to two significant figures, the net energy absorbed is1.1 \times 10^{-19} \text{ J}..
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