Question

Activity 26-4. Wave aspects of matter and of light [Accompanies Sections 26-3 and 26-4] (a) Rank the following particles in order of their de Broglie wavelength, from longest wavelength to shortest wavelength. If any two particles have the same de Broglie wavelength, state this. Explain how you made your ranking. (i) A proton (mass 1.67 x 10-27 kg) moving north at 1.0 x 10 m/s (ii) A proton (mass 1.67 x 10-27 kg) moving west at 2.0 x 10 m/s (iii) An electron (mass 9.11 x 10-31 kg) moving south at 1.0 x 10 m/s (iv) An electron (mass 9.11 10-31 kg) moving east at 2.0 x 10² m/s (v) An electron (mass 9.11 x 10-31 kg) moving southwest at 2.0 x 103 m/s (b) Fill in the blanks with the phrase a photon, the phrase an electron, the phrase either a photon or an electron, or the phrase don't know. (i) If the momentum of increases, its wavelength decreases. (ii) If the energy of increases, its wavelength decreases. (iii) If the momentum of increases, its energy increases. (iv) If the momentum of doubles, its energy doubles. (v) If the wavelength of increases, its speed decreases.

Answer 1

$\lambda$ = h / mv

(i) A proton (mass 1.67 x 10-27 kg) moving north at 1.0 x 10 m/s 0.397 nm (ii) A proton (mass 1.67 x 10-27 kg) moving west at 2.0 x 103 m/s 0.1985 nm (iii) An electron (mass 9.11 10-31 kg) moving south at 1.0 x 10 m/s 728.57 nm (iv) An electron (mass 9.11 x 10-31 kg) moving east at 2.0 x 10 m/s 364.3 nm (v) An electron (mass 9.11 10-31 kg) moving southwest at 2.0 x 10² m/s 364.3 nm

here is the ranking

(iii) > (iv) = (v) > (i) > (ii)

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