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JEE Main 2004 (AIEEE) · Photoelectric Effect: Einstein's Equation

Photoelectric Effect: Einstein's Equation question from JEE Main 2004 (AIEEE)

Q165JEE Main 2004 · AIEEEEasy

Photoelectric Effect: Einstein's Equation

The work function of a substance is $4.0\text{ eV}.$ The longest wavelength of light that can cause photo- electron emission from this substance is approximately.

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Answer: (a)

Longest wavelength = threshold wavelength: $\lambda_0 = \frac{hc}{\phi}$
$\lambda_0 = \frac{1240\text{ eV nm}}{4.0\text{ eV}} = 310\text{ nm}$
So the answer is (a) $310\text{ nm}$ .

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