NEET2015PhysicsDual Nature of MatterActual
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:
Options
- A< 2.8 × 10 - 9 m
- B≥ 2.8 × 10 - 9 m
- C≤ 2.8 × 10 - 12 m
- D< 2.8 × 10 - 10 m
Correct answer
B. ≥ 2.8 × 10 - 9 m
Step-by-step solution
K E m a x = h c λ - Ψ ⇒ K E m a x = 1240 500 - 2.28 ⇒ K E m a x = 2.48 - 2.28 = 0.2   e V λ m i n = h 2 m KE max = 20 3 × 10 - 34 2 × 9 × 10 - 31 × 0.2 × 1.6 × 10 - 19 λ m i n = 25 9 × 10 - 9 = 2.80 × 10 - 9   m So, λ ≥ 2.8 × 10 - 9   m .