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Question
Calculate the de Broglie wavelength of a proton whose kinetic energy is equal to 81.9 × 10–15 J.
(Given: mass of proton is 1836 times that of electron).
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Solution
mp = 1.67 × 10–27 kg
K.E = 81.9 × 10–15 J
de-Broglie wavelength of proton,
λ = `"h"/sqrt(2"mK")`
= `(6.6 xx 10^-34)/sqrt(2 xx 1.67 xx 10^-27 xx 81.9 xx 10^-15)`
= `(6.6 xx 10^-34)/(1.6539 xx 10^-20)`
= 3.99 × 10–14
λ = 4 × 10–14 m
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