The wavelength of an X-ray beam is 10 A. The mass of a fictitious particle having the same energy as that of the X-ray photons is x/3h kg. The value of x is __________. (h = Planck's constant) Numerical answer type. Work it out, then open the answer.

Answer: 10. Equate energies: mc² = (hc)/(λ) ⇒ m = (h)/(λ c) m = h10⁻⁹× 3×10⁸ = h/0.3 = 10/3h So x = 10.

The wavelength of an X-ray beam is 10 A. The mass of a fictitious… | JEE Main 2021 (25 Feb, Shift 2)

Q27JEE Main 2021 · 25 FEB · SHIFT 2Medium

Photons: Energy, Momentum & Radiation Pressure

The wavelength of an X-ray beam is 10 $\mathring{A}$ . The mass of a fictitious particle having the same energy as that of the X-ray photons is $\frac{x}{3}h$ kg. The value of x is __________. (h = Planck's constant)

Numerical answer type. Work it out, then open the answer.

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Answer: 10

Equate energies: $mc^2 = \dfrac{hc}{\lambda} \Rightarrow m = \dfrac{h}{\lambda c}$
$m = \dfrac{h}{10^{-9}\times 3\times10^{8}} = \dfrac{h}{0.3} = \dfrac{10}{3}h$
So $x = 10$ .

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