If the wavelength of a photon is \(4000 Å\), then its energy will be

If the wavelength of a photon is \(4000 Å\), then its energy will be
  1. \(4.95 \times 10^{-19} \mathrm{~J}\)
  2. \(5.95 \times 10^{-19} \mathrm{~J}\)
  3. \(3.95 \times 10^{-19} \mathrm{~J}\)
  4. \(6.95 \times 10^{-19} \mathrm{~J}\)

Solution

Wavelength of photon, $\lambda=4000 \, \text{Å}=4 \times 10^{-7} \, \text{m}$ Energy of photon, $E=\frac{h c}{\lambda}$ $\begin{aligned} & =\frac{6.62 \times 10^{-34} \times 3 \times 10^{8}}{4 \times 10^{-7}} \\ & =4.96 \times 10^{-19} \, \text{J} \approx 4.95 \times 10^{-19} \, \text{J} \end{aligned}$

Asked in: AP EAMCET 2020 (21 Sep Shift 1)

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