The work function of a surface of a photosensitive material is 6 . 2 eV . The wavelength of incident radiation for which the stopping potential is 5 V lies in the

Question

The work function of a surface of a photosensitive material is 6 . 2 eV . The wavelength of incident radiation for which the stopping potential is 5 V lies in the, ultraviolet region, visible region, infrared region, x - rays region

MARKS App · Accepted Answer

Work function, ϕ 0 = 6 .2 eV Stopping potential V 0 = 5 V As eV 0 = hv - ϕ 0 or eV 0 + ϕ 0 = hc λ or λ = hc eV 0 + ϕ 0 λ = 6 .62 × 10 - 34 J s × 3 × 10 8 m s - 1 1 .6 × 10 - 19 × 5 J + 6 .2 × 1 .6 × 10 - 19 J = 6 .62 × 10 - 34 × 3 × 10 8 1 .6 × 10 - 19 ( 5 + 6 .2 ) m = 19 .86 × 10 - 26 17 .92 × 10 - 19 = 1 .10 × 10 - 7 m . Thus the wavelength of the incident radiation lies in the ultraviolet region.

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