Light of wavelength $λ$ falls on

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Target Exam

CUET

Subject

Physics

Chapter

Dual Nature of Radiation and Matter

Question:

Light of wavelength $λ$ falls on a metal having work function $\frac{hc}{λ_0}$. Photoelectric effect will take place only if:

Options:

$λ≥λ_0$

$λ≥2λ_0$

$λ≤λ_0$

$λ=4λ_0$

Correct Answer:

$λ≤λ_0$

Explanation:

According to Einstein’s photoelectric equation

$K=\frac{hc}{λ}-\frac{hc}{λ_0}$

K is positive, i.e., photoelectric emission will take place if

$\frac{hc}{λ}-\frac{hc}{λ_0}$ or $λ≤λ_0$