Light of wavelength 500 nm is incident on a metal with work function 2.28 eV.

⇦

⇨

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) ≤2.8×10⁻¹² m
(c) < 2.8×10⁻¹⁰ m
(d) <2.8×10⁻⁹ m

Correct Answer:

≥2.8×10⁻⁹ m

Explanation:

Given : Work function ɸ of metal = 2.28 eV
Wavelength of light λ = 500 nm = 500 x 10⁻⁹ m
KE(max) = (hc / λ) – ɸ
KE(max) = [(6.6 × 10⁻³⁴ × 3 × 10⁸) / 5 × 10⁻⁷] – 2.82 = 2.48 – 2.28 = 0.2 eV
λ(min) = h / p = h / √[2m KE(max)] = (20/3) × 10⁻³⁴ / √(2 × 9 × 10⁻³¹ × 0.2 × 1.6 × 10⁻¹⁹)
λ(min) = (25 / 9) × 10⁻⁹ = 2.80 × 10⁻⁹ nm
Therefore, λ ≥ 2.8 × 10⁻⁹ nm.

Related Questions:

1. In p- type semiconductor, the acceptor level lies
2. Water falls from a height of 60m at the rate of 15 kg/s to operate a turbine
3. The magnifying power of a convex lens of focal length 10 cm, when the image
4. A Carnot engine, having an efficiency of η=1/10 as heat engine, is used
5. The heart of a man pumps 5 litres of blood through the arteries per minute at

Topics: Dual Nature of Matter and Radiation (150)
Subject: Physics (2479)

---

Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score

18000+ students are using NEETLab to improve their score. What about you?

Solve Previous Year MCQs, Mock Tests, Topicwise Practice Tests, Identify Weak Topics, Formula Flash cards and much more is available in NEETLab Android App to improve your NEET score.

---

Share this page with your friends