Question

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) ____________.

Options

• 310 nm

• 3100 nm

• 966 nm

• 31 nm

Answer 1

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) 310 nm.

Explanation:

`"Work function,"  phi = "hc"/lambda_0`

`therefore lamda_0 = "hc"/phi = "hc"/(4"e")`

`= (1240 xx 10^-9)/4`

`= 3.10 xx 10^-7  "m"`

`= 310  "nm"`