Electromagnetic Waves

JEE Main level, numerical answer, medium

161 of 165

Question 161 of 165

The wavelength of an X-ray beam is 10Å10Å. The mass of a fictitious particle having the same energy as that of the X-ray photons is x3hkg.\dfrac{x}{3}hkg. The value of xx is ___ . (h=h=Planck's constant)

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Answer: 10

hcλ=mc2\dfrac{hc}{\lambda }=m{c}^{2}
⇒m=hcλ=h3×108×10×10−10=10h3kg\Rightarrow m=\dfrac{h}{c\lambda }=\dfrac{h}{3\times {10}^{8}\times 10\times {10}^{-10}}=\dfrac{10h}{3}kg

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