Monochromatic radiation emitted when an electron in hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be 3.57 V. The threshold frequency of the material is

Question

Dr. Abubacker · Accepted Answer

[Solution from source] The n = 2 → 1 transition in hydrogen emits a 10.2 eV photon. Work function = 10.2 − 3.57 = 6.63 eV = 6.63 × 1.6 × 10⁻¹⁹ J. Threshold frequency ν₀ = φ/h = (6.63 × 1.6 × 10⁻¹⁹)/(6.63 × 10⁻³⁴) = 1.6 × 10¹⁵ Hz. Using the full 10.2 eV gives about 2.5 × 10¹⁵ Hz, which is the photon frequency, not the threshold. Answer (4).

Q. Monochromatic radiation emitted when an electron in hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be 3.57 V. The threshold frequency of the material is

Explanation

Reviewed by Dr. Abubacker

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