The work function of a photosensitive material is 4.0 eV. The longest wavelength of light that can cause photon emission from the substance is (approximately)

Question

Question

Answer 1

CONCEPT:

The work function is written as;

\(ϕ = \frac{hc}{λ}\)

Here we have h is the Planck's constant, c is the velocity of light and λ is the wavelength.

CALCULATION:

Given: ϕ = 4.0 eV

As we know, hc = 1240 × 10^-9 eV-m

Now, \(ϕ = \frac{hc}{λ}\) ----(1)

On putting the values in equation values we have;

\(4.0 = \frac{1240}{λ}\times{10^{-9}}\)

⇒ λ = 310 nm

Hence, option 2) is the correct answer.

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