Light of wavelength 500 nm is incident on a metal with work function 2 . 28 eV . The de Broglie wavelength…

Light of wavelength 500 nm is incident on a metal with work function 2.28 eV. The de Broglie wavelength of the emitted electron is:
  1. <2.8×10-9 m
  2. ≥2.8×10-9 m
  3. ≤2.8×10-12 m
  4. <2.8×10-10 m

Solution

KEmax=hcλ-Ψ
⇒KEmax=1240500-2.28
⇒KEmax=2.48-2.28=0.2 eV
λmin=h2mKEmax=203×10-342×9×10-31×0.2×1.6×10-19
λmin=259×10-9=2.80×10-9 m
So, λ≥2.8×10-9 m.

Asked in: NEET 2015 (Phase 2)

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