The wavelength of a photon is needed to remove a proton from a nucleus which is bound to the nucleus with 1 MeV energy is nearly?
Correct answer: B. 1.2 x 10^-3 nm
- A. 1.2 nm
- B. 1.2 x 10^-3 nm
- C. 1.2 x 10^-6 nm
- D. 1.2 x 10^1 nm
Explanation
Energy needed to remove the proton equals 1 MeV.1 MeV equals 1 times 10 to the power 6 electron volts.1 electron volt equals 1.6 times 10 to the power minus 19 joule, therefore1 MeV equals 1.6 times 10 to the power minus 13 joule.Use the relation lambda equals h c divided by E.h equals 6.63 times 10 to the power minus 34 joule second.c equals 3 times 10 to the power 8 metre per second.Multiply h and c:6.63 times 10 to the power minus 34 times 3 times 10 to the power 8 equals 1.99 times 10 to the power minus 25 joule metre.Divide by the energy 1.6 times 10 to the power minus 13 joule:1.99 times 10 to the power minus 25 divided by 1.6 times 10 to the power minus 13 equals 1.24 times 10 to the power minus 12 metre.Convert metre to nanometre: 1 metre equals 1 times 10 to the power 9 nanometre, so1.24 times 10 to the power minus 12 metre equals 1.24 times 10 to the power minus 3 nanometre.Thus the required wavelength is about 1.2 times 10 to the power minus 3 nanometre.
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Classical physics cannot explain blackbody radiation and related observations, leading to Planck’s quantum theory, in which energy is emitted or absorbed in discrete packets. Photons provide the particle model of light, with energy and momentum linked to frequency and wavelength, including the photoelectric effect and its threshold frequency.
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